Optionally crosslinkable coatings for orthodontic devices

ABSTRACT

Coatings for hard tissue and surfaces of the oral environment are provided that reduce adhesion of bacteria and proteinaceous substances to these surfaces. Methods of reducing adhesion of these materials to such surfaces, and polymers for incorporation into such coatings are also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 08/467,421filed Jun. 6, 1995, now abandoned, which is a divisional application ofU.S. Ser. No. 08/347,861, filed Dec. 1, 1994, now abandoned which is acontinuation-in-part, application of U.S. application Ser. No.08/163,028 filed Dec. 6, 1993, now pending.

FIELD OF THE INVENTION

This invention relates to coatings on hard tissue surfaces or surfacesof the oral environment. More specifically, this invention relates tosubstantive coatings for hard tissue surfaces or surfaces of the oralenvironment.

BACKGROUND OF THE INVENTION

Plaque is a common factor in caries, gum disease and discoloration ofteeth and greatly contributes to their development. Plaque is initiatedwhen cariogenic bacteria adhere to pellicle, a proteinaceous film on thesurface of teeth. Plaque, in turn, acts as a nucleus for the formationof calculus. As calculus matures and hardens it tends to stain due tothe absorption of dietary chromagens. Additionally, oral restorativematerials may be inherently susceptible to build-up of stain fromdietary chromagens. It is desirable to have a means to avoid stainabsorption and adherence of bacteria to hard tissue and surfaces of theoral environment.

Silicone oils, because of their hydrophobic nature, have been suggestedfor inclusion in dentrifices to inhibit the staining process. Howevertheir adhesion and retention on tooth surfaces is typically quite low.

U.S. Pat. No. 5,078,988 to Lin et al. discloses dentifrices includingmodified aminoalkyl silicones. The modified silicones are said to form ahydrophobic layer on the teeth for prevention of caries and stain. PCTpatent application number WO 91/13608 to Rolla et al. disclosesdentifrices comprising a liquid silicone oil and a fat-solubleantibacterial agent, which is described as being useful for protectionof teeth against plaque formation due to a slow release of antibacterialagent into the saliva.

U.S. Pat. No. 4,981,903 to Garbe et al. discloses pressure-sensitive ornon-pressure sensitive adhesive compositions comprising a vinylpolymeric backbone with grafted pendant siloxane polymeric moieties.These compositions are disclosed to be useful as good topicalapplication binding materials for application in cosmetics andmedicaments, and also as sealant compositions for porous materials suchas paper and wood. See col. 3, lines 25 through 31. U.S. Pat. No.4,972,037 to Garbe et al. discloses compositions useful as an adhesiveat room temperature which comprise a copolymer having both pendantfluorochemical groups and pendant polysiloxane grafts. Thesecompositions are also useful in topical applications, including theapplication of cosmetics and medicaments and for sealant compositionsfor porous materials such as paper and wood. See col. 3, lines 25through 33. U.S. Pat. No. 4,981,902 to Mitra, et. al. disclosesnon-pressure-sensitive adhesive acrylate or methacryate polymers havingpendant polysiloxane grafts. The polymers comprise monomers having polarfunctionality, and are described as useful in coating compositions foranimal bodies.

U.S. Pat. No. 4,693,935 to Mazurek discloses pressure-sensitive adhesivecompositions comprising a copolymer having a vinyl polymeric backbonehaving grafted thereto polysiloxane moieties. U.S. Pat. No. 4,728,571 toClemens et al. discloses release coating compositions comprisingpolysiloxane grafted copolymer and blends thereof on sheet materials.

SUMMARY OF THE INVENTION

The present invention provides coatings on hard tissue surfaces orsurfaces of the oral environment, which coating comprises a polymercomprising repeating units

A) 1-80% by weight of a polar or polarizable group

B) 0-98% by weight of a modulating group

C) 1-40% by weight of a hydrophobic graft polysiloxane chain havingmolecular weight of at least 500.

The present invention also provides dental compositions suitable forcoating human oral surfaces comprising a polymer comprising repeatingunits

A) 1-80% by weight of a polar or polarizable group

B) 0-98% by weight of a modulating group

C) 1-40% by weight of a hydrophobic graft polysiloxane chain havingmolecular weight of at least 500,

wherein said polymer additionally contains at least one silane moietythat is capable of undergoing a condensation reaction.

These compositions optionally may also comprise catalysts to promote thesilane condensation reaction, and optionally an additional compoundcomprising at least two condensation silicone reaction sites that arecapable of undergoing a condensation reaction. This additional compoundacts as a bridging compound between the polymers described above aftercompletion of the condensation reaction.

Additionally, it has surprisingly been found that significantenhancement of resistance to stain and bacterial adhesion may beprovided by treatment of surfaces having the above coating with asurfactant.

The present invention also provides in another embodiment polymers forcoating hard tissue surfaces or surfaces of the oral environment thatare crosslinkable on the surface.

In yet another embodiment, dental devices are provided that have acoating comprising the polymer system as noted above.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a photograph of a tooth chip having a coating of the presentinvention applied thereto, which shows no retention of a dye to thetooth material.

FIG. 2 is a photograph of a tooth chip that has a coating of comparativeexample 1 of the present invention applied thereto, and which showsretention of a dye to the tooth material.

FIG. 3 is a chart showing the relative level of adherence of proteins orbacteria to enamel particles rinsed with phosphate buffered saline.

FIG. 4 is a chart showing the relative level of adherence of proteins orbacteria to enamel particles rinsed with an NP-40 surfactant-containingsolution.

DETAILED DESCRIPTION

This invention relates to coatings on hard tissues such as dentin,enamel, cementum and bone. Alternatively, the coating may be provided onother surfaces of the oral environment, including surfaces of dentalrestorations, orthodontic devices or prostodontic devices. Dentalrestorations include restorations fabricated from resin-basedcomposites, amalgam, glass ionomers, ceramics and a variety of hybridmaterials derived from these. Orthodontic devices include orthodonticbrackets, wires and the like. Prostodontic devices include dentalbridges, crowns, dentures, and the like.

The coatings are provided in an amount sufficient to provide resistanceof the coated surface to bacterial adhesion, plaque formation orstaining from foods or dyes. The coating may be provided as a continuousor semi-continuous layer. Preferably, the coating is applied in anamount at least sufficient to provide a substantially continuousmonolayer of polymer as described herein on the coated surface.

The coatings provided in accordance with the invention are highlysubstantive to the aforementioned surfaces. The coatings have lowfrictional coefficients and have high resistance to plaque, bacteria,food stains and the like.

It has surprisingly further been discovered that when a surface having acoating as described herein is treated with a composition comprising asurfactant, enhanced resistance to adhesion of bacteria andproteinaceous substances on the surface is observed. Thesurfactant-treatment step provides this surprising benefit even if thecoated surface is exposed to bacteria and proteinaceous substancesbefore the surfactant-treatment step. Thus, a coating as describedherein that has been treated with a surfactant-containing composition isapparently physically different from coatings that have not been treatedwith a surfactant-containing composition. While not being bound bytheory, it is believed that the surfactant treatment orients thepolysiloxane component of the polymer of the coating, thereby enhancingthe bacteria adhesion and stain resistant properties of the coating.

The surfactant treatment can be applied (i) as part of the initialcoating (ii) subsequent to initial coating, but before exposing thecoated surface to undesirable oral organisms of proteinaceoussubstances, or (iii) after exposing the coated surface to bacteria andthe like. In the last case, the surfactant treatment can be reappliedfrom time to time.

The coating of the present invention comprises a vinylic copolymerhaving repeat units of A, B and C, where A is derived from anethylenically unsaturated monomer containing at least one polar orpolarizable group, B is derived from an ethylenically unsaturatedmonomer optionally containing modifying groups and C is derived from anethylenically unsaturated organosiloxane chain. Preferably, the polymeris less than 0.1% soluble in water.

More specifically, the unit A is derived from vinylic monomers such asacrylates, methacrylates, crotonates, itaconates and the like. The polargroups can be acidic, basic or salt. These groups can also be ionic orneutral.

Examples of polar or polarizable groups include neutral groups such ashydroxy, thio, substituted and unsubstituted amido, cyclic ethers (suchas oxanes, oxetanes, furans and pyrans), basic groups (such asphosphines and amines, including primary, secondary, tertiary amines),acidic groups (such as oxy acids, and thiooxyacids of C, S, P, B) andionic groups (such as quarternary ammonium, carboxylate salt, sulfonicacid salt and the like) and the precursors and protected forms of thesegroups. Additionally, A could be a macromonomer. More specific examplesof such groups follow.

The A units may be derived from mono- or multifunctional carboxyl groupcontaining molecules represented by the general formula:

    CH.sub.2 ═CR.sup.2 G--(COOH).sub.d

where R² ═H, methyl, ethyl, cyano, carboxy or carboxymethyl, d=1-5 and Gis a bond or a hydrocarbyl radical linking group containing from 1-12carbon atoms of valence d+1 and optionally substituted with and/orinterrupted with a substituted or unsubstituted heteroatom (such as O,S, N and P). Optionally, this unit may be provided in its salt form. Thepreferred monomers in this class are acrylic acid, methacrylic acid,itaconic acid and N-acryloyl glycine.

The A units may, for example, be derived from mono- or multifunctionalhydroxy group containing molecules represented by the general formula:

    CH.sub.2 ═CR.sup.2 --CO--L--R.sup.3 --(OH).sub.d

where R² ═H, methyl, ethyl, cyano, carboxy or carboxyalkyl, L=O, NH,d=1-5 and R³ is a hydrocarbyl radical of valence d+1 containing from1-12 carbon atoms. The preferred monomers in this class are hydroxyethyl(meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl(meth)acrylate, glycerol mono(meth)acrylate, tris(hydroxymethyl)ethanemonoacrylate, pentaerythritol mono(meth)acrylate, N-hydroxymethyl(meth)acrylamide, hydroxyethyl (meth)acrylamide and hydroxypropyl(meth)acrylamide.

The A unit may alternatively be derived from mono- or multifunctionalamino group containing molecules of the general formula:

    CH.sub.2 ═CR.sup.2 --CO--L--R.sup.3 --(NR.sup.4 R.sup.5).sub.d

where R², L, R³, and d are as defined above and R⁴ and R⁵ are H or alkylgroups of 1-12 carbon atoms or together they constitute a carbocyclic orheterocyclic group. Preferred monomers of this class are aminoethyl(meth)acrylate, aminopropyl (meth)acrylate, N,N-dimethylaminoethyl(meth)acrylate, N,N-diethylaminoethyl (meth)acrylate,N,N-dimethylaminopropyl (meth)acrylamide, N-isopropylaminopropyl(meth)acrylamide and 4-methyl-1-acryloyl-piperazine.

The A unit may also be derived from alkoxy substituted (meth)acrylatesor (meth)acrylamides such as methoxyethyl (meth)acrylate,2(2-ethoxyethoxy)ethyl (meth)acrylate, polyethylene glycolmono(meth)acrylate or polypropylene glycol mono(meth)acrylate.

A units may be derived from substituted or unsubstituted ammoniummonomers of the general formula:

    CH.sub.2 ═CR.sup.2 --CO--L--R.sup.3 --(.sup.⊕ NR.sup.4 R.sup.5 R.sup.6).sub.d Q.sup.-

where R², R³, R⁴, R⁵, L and d are as defined above, and where R⁶ is H oralkyl of 1-12 carbon atoms and Q⁻ is an organic or inorganic anion.Preferred examples of such monomers are 2-N,N,N-trimethylammonium ethyl(meth)acrylate, 2-N,N,N-triethylammonium ethyl (meth)acrylate,3-N,N,N-trimethylammonium propyl (meth)acrylate,N(2-N',N',N'-trimethylammonium) ethyl (meth)acrylamide, N-(dimethylhydroxyethyl ammonium) propyl (meth)acrylamide etc. where the counterionmay be fluoride, chloride, bromide, acetate, propionate, laurate,palmitate, stearate etc. The monomer can also be N,N-dimethyl diallylammonium salt of an organic or inorganic counterion.

Ammonium group containing polymers can also be prepared by using as theA unit any of the amino group containing monomer described above, andacidifying the resultant polymers with organic or inorganic acid to a pHwhere the pendant amino groups are substantially protonated. Totallysubstituted ammonium group containing polymers may be prepared byalkylating the above described amino polymers with alkylating groups,the method being commonly known in the art as the Menschutkin reaction.

The A unit of the invention can also be derived from sulfonic acid groupcontaining monomers, such as vinyl sulfonic acid, styrene sulfonic acid,2-acrylamido-2-methyl propane sulfonic acid, allyloxybenzene sulfonicacid, and the like. Alternatively, the A unit may be derived fromphosphorous acid or boron acid group-containing monomers. These monomersmay be used in the protonated acid form as monomers and thecorresponding polymers obtained may be neutralized with an organic orinorganic base to give the salt form of the polymers.

The unit B is derived from acrylate or methacrylate or other vinylpolymerizable starting monomers and optionally contains functionalitiesthat modulate properties such as glass transition temperature,solubility in the carrier medium, hydrophilic-hydrophobic balance andthe like.

Examples of unit B monomers include the lower to intermediatemethacrylic acid esters of 1-12 carbon straight, branched or cyclicalcohols. Other examples of B unit monomers include styrene, vinylesters, vinyl chloride, vinylidene chloride, acryloyl monomers and thelike.

Further examples of B monomers are acrylic or methacrylic acid esters of1,1-dihydroperfluoroalkanols (1) and homologs (2), ##STR1## where p ands are at least 1 and r is 1 to 6 Preferred polymerized A monomerbackbone compositions include polymers of fluoroacrylates 8-13. ##STR2##

B may also optionally be derived from macromonomers such as thosederived from styrene, α-methystyrene, vinyl toluene or methylmethacrylate. Preferred such macromonomers have a molecular weight of500-100,000.

The unit C is derived from an ethylenically unsaturated preformedorganosiloxane chain. The molecular weight of this unit is generallyabove 500.

The unit C of the invention may be derived from a monomer having thegeneral formula

    X(Y).sub.n- Si(R).sub.3-m Z.sub.m

wherein

X is a vinyl group copolymerizable with the A and B monomers;

Y is a divalent linking group (e.g., alkylene, arylene, alkarylene, andaralkylene of 1 to 30 carbon atoms) and incorporating heteroatoms e.g.O, N, S, P. Examples are ester, amide, urethane, urea groups.

n is zero or 1;

m is an integer of from 1 to 3;

R is hydrogen, lower alkyl (e.g., 1 to 4 carbon atoms, methyl, ethyl, orpropyl), aryl (e.g., 6 to 20 carbon atoms, phenyl or substitutedphenyl), or alkoxy (preferably lower alkoxy of 1 to 4 carbon atoms);

Z is a monovalent siloxane polymeric moiety having a number averagemolecular weight above about 500 and is essentially unreactive undercopolymerization conditions;

The preferred C monomer may be further defined as having an X groupwhich has the general formula ##STR3## wherein R⁷ is a hydrogen atom ora COOH group and R⁸ is a hydrogen atom, a methyl group, or a CH₂ COOHgroup.

The Z group of the C monomer has the general formula ##STR4## where R⁹and R¹¹ are independently lower alkyl, aryl, or fluoroalkyl, where loweralkyl and fluoroalkyl both refer to alkyl groups having from one tothree carbon atoms and where aryl refers to phenyl or substituted phenyl(of up to 20 carbon atoms). R¹⁰ may be alkyl (of 1 to 20 carbon atoms),alkoxy (of 1 to 20 carbon atoms), alkylamino (of 1 to 20 carbon atoms),aryl (of up to 20 carbon atoms), hydroxyl, or fluoroalkyl (of 1 to 20carbon atoms), and e is an integer from about 5 to about 700.Preferably, the C monomer has a general formula selected from the groupconsisting of the following, where m is 1, 2, or 3, g is zero or 1, R¹¹may be alkyl (of 1 to 10 carbon atoms) or hydrogen, f is an integer from2 to 6, h is an integer from zero to 2, and X, R, and Z are as definedabove: ##STR5##

Particularly preferred polymers for use in the present invention havethe composition wherein

the A group is derived from mono- or multifunctional carboxylgroup-containing molecules represented by the general formula:

    CH.sub.2 ═CR.sup.2 G--(COOH).sub.d

where

R² ═H or methyl

d=1, and

G is a bond or a hydrocarbyl radical linking group containing from 1-12carbon atoms of valence d+1, or a salt thereof; and

the C group is derived from a monomer of the formula ##STR6## wherein Xis a vinyl group copolymerizable with the A and B monomers;

m is an integer of from 1 to 3;

R is hydrogen, lower alkyl;

Z is a monovalent siloxane polymeric moiety having a number averagemolecular weight above about 500 and is essentially unreactive undercopolymerization conditions.

Monomers used to provide the C unit of this invention are terminallyfunctional polymers having a single functional group (vinyl,ethylenically unsaturated, acryloyl, or methacryloyl group) and aresometimes termed macromonomers or "macromers". Such monomers are knownand may be prepared by the method disclosed by Milkovich et al., asdescribed in U.S. Pat. Nos. 3,786,116 and 3,842,059. The preparation ofpolydimethylsiloxane macromonomer and subsequent copolymerization withvinyl monomer have been described in several papers by Y. Yamashita etal., Polymer J. 14, 913 (1982); ACS Polymer Preprints 25 (1), 245(1984); Makromol. Chem. 185, 9 (1984)!. This method of macromonomerpreparation involves the anionic polymerization ofhexamethylcyclotrisiloxane monomer (D₃) to form living polymer ofcontrolled molecular weight, and termination is achieved viachlorosilane compounds containing a polymerizable vinyl group. Freeradical copolymerization of the monofunctional siloxane macromonomerwith vinyl monomer or monomers provides siloxane-grafted copolymer ofwell-defined structure, i.e., controlled length and number of graftedsiloxane branches.

Suitable monomers for use in the above mentioned anionic polymerizationare, in general, diorganocyclosiloxanes of the formula ##STR7## where R⁹and R¹¹ are as previously defined and where e is an integer of 3 to 7.Preferred are the cyclic siloxanes where e is 3 or 4 and R⁹ and R¹¹ areboth methyl, these cyclic siloxanes being hereafter designated D₃ andD₄, respectively. D₃, which is a strained ring structure, is especiallypreferred.

Initiators of the anionic polymerization are chosen such thatmonofunctional living polymer is produced. Suitable initiators includealkali metal hydrocarbons such as alkyl or aryl lithium, sodium, orpotassium compounds containing up to 20 carbon atoms in the alkyl oraryl radical or more, preferably up to 8 carbon atoms. Examples of suchcompounds are ethylsodium, propylsodium, phenylsodium, butylpotassium,octylpotassium, methyllithium, ethyllithium, n-butyllithium,sec-butyllithium, tert-butyllithium, phenyllithium, and2-ethylhexyllithium. Lithium compounds are preferred as initiators. Alsosuitable as initiators are alkali metal alkoxides, hydroxides, andamides, as well as triorganosilanolates of the formula ##STR8## where Mis alkali metal, tetraalkylammonium, or tetraalkylphosphonium cation andwhere R⁹, R¹⁰, and R¹¹ are as previously defined. The preferredtriorganosilanolate initiator is lithium trimethylsilanolate (LTMS). Ingeneral, the preferred use of both strained cyclic monomer and lithiuminitiator reduces the likelihood of redistribution reactions and therebyprovides siloxane macromonomer of narrow molecular weight distributionwhich is reasonably free of unwanted cyclic oligomers.

Molecular weight is determined by the initiator/cyclic monomer ratio,and thus the amount of initiator may vary from about 0.004 to about 0.4mole of organometallic initiator per mole of monomer. Preferably, theamount will be from about 0.008 to about 0.04 mole of initiator per moleof monomer.

For the initiation of the anionic polymerization, an inert, preferablypolar organic solvent can be utilized. Anionic polymerizationpropagation with lithium counterion requires either a strong polarsolvent such as tetrahydrofuran, dimethyl sulfoxide, orhexamethylphosphorous triamide, or a mixture of such polar solvent withnonpolar aliphatic, cycloaliphatic, or aromatic hydrocarbon solvent suchas hexane, heptane, octane, cyclohexane, or toluene. The polar solventserves to "activate" the silanolate ion, making propagation possible.

Generally, the polymerization can be carried out at a temperatureranging from about -50° C. to about 100° C., preferably from about -20°C. to about 30° C. Anhydrous conditions and an inert atmosphere such asnitrogen, helium, or argon are required.

Termination of the anionic polymerization is, in general, achieved viadirect reaction of the living polymeric anion with halogen-containingtermination agents, i.e., functionalized chlorosilanes, to producevinyl-terminated polymeric monomers. Such terminating agents may berepresented by the general formula X(Y)_(n) Si(R)_(3-m) Cl_(m), where mis 1, 2, or 3 and where X, Y, n, and R have been previously defined. Apreferred terminating agent is methacryloxypropyldimethylchlorosilane.The termination reaction is carried out by adding a slight molar excessof the terminating agent (relative to the amount of initiator) to theliving polymer at the polymerization temperature. According to theaforementioned papers by Y. Yamashita et al., the reaction mixture maybe ultrasonically irradiated after addition of the terminating agent inorder to enhance functionality of the macromonomer. Purification of themacromonomer can be effected by addition of methanol.

The copolymer used in this invention is conveniently prepared bycopolymerizing the starting monomer units A, B and C by standardpolymerizing techniques.

The polymer may also contain one or more crosslinkable groups for laterfixing of the coating or surface composition by a subsequentcrosslinking reaction after the polymer has been placed on the intendedsubstrate. Copolymers where the group B contains a crosslinkable groupcan be prepared by reacting an electrophilic or nucleophilic moiety ofthe copolymer with another compound containing the appropriate reactivegroup and at least one crosslinkable group, such as an ethylenic groupor an epoxy group. The electrophilic or nucleophilic moiety can in somecases be the same as that present in unit A of the copolymer.

The present invention therefore also contemplates new polymerscomprising repeating units

A) 1-80% by weight of a polar or polarizable group

B) 0-98% by weight of a modulating group

C) 1-40% by weight of a hydrophobic graft polysiloxane chain havingmolecular weight of at least 500, wherein the polymer additionallycomprises pendent crosslinkable groups.

The crosslinkable group is capable of undergoing a free-radical orcationic crosslinking reaction. Suitable crosslinkable groups include,but are not limited to, polymerizable ethylenically unsaturated groupsand polymerizable epoxy groups. Ethylenically unsaturated groups arepreferred, especially those that can be polymerized by means of afree-radical mechanism, examples of which are substituted andunsubstituted acrylates, methyacrylates, alkenes and acrylamides. Inaqueous systems, polymerizable groups that are polymerized by a cationicmechanism, e.g., polymerizable ethylenically unsaturated groups such asvinyl ether groups and polymerizable epoxy groups, are less preferredsince a free-radical mechanism is typically easier to employ in suchsystems than a cationic mechanism.

Crosslinkable polymers can be prepared according to a variety ofsynthetic routes, including, but not limited to reacting a polymerhaving electrophilic or neucleophilic groups with less than an oneequivalent of a suitable compound in order to form pendent crosslinkablegroups, thereby leaving electrophilic or neucleophilic groups unreacted.Alternatively, the appropriate monomers may be copolymerized with apendent crosslinkable group already present in the monomer. The reactionin this process must be carefully controlled to avoid complete reactionof all groups in the polymerization stage, or the reaction used to formthe polymer must be different from the reaction used to form crosslinksbetween the polymers.

The first synthetic route described above for making the crosslinkablepolymer can presently be carried out by the use of a "couplingcompound", i.e., a compound containing both a pendent crosslinkablegroup and a reactive group capable of reacting with the polymer througha functionality existing on a starting material polymer in order to forma covalent bond between the coupling compound and the electrophilic orneucleophilic group, thereby linking the pendent crosslinking group tothe backbone of the polymer. Suitable coupling compounds are organiccompounds, optionally containing non-interfering substituents and/ornon-interfering linking groups between the pendent crosslinking groupand the reactive group.

Coupling compounds suitable for use for preparing polymers of thepresent invention include compounds that contain at least one groupcapable of reacting with a polar group in order to form a covalent bond,as well as at least one polymerizable ethylenically unsaturated group.When the polar group is carboxyl, a number of groups are capable ofreacting with it, including both electrophilic and nucleophilic groups.Examples of such groups include the following moieties, and groupscontaining these moieties: --OH, --NH₂, --NCO, --COCl, and ##STR9## Whenthe attaching site is an alcohol, a number of groups are capable ofreacting with the alcohol. Examples of such groups include the followingmoieties, and groups containing these moieties: --NCO, --COCl, ##STR10##Examples of suitable coupling compounds to attach crosslinkable groupsinclude, for example, acryloyl chloride, methacryloyl chloride, vinylazalactone, allyl isocyanate, 2-hydroxyethylmethacrylate,2-aminoethylmethacrylate, and 2-isocyanatoethylmethacrylate. Otherexamples of suitable coupling compounds include those described in U.S.Pat. No. 4,035,321. Examples of preferred coupling compounds include,for example, the following methacrylate compounds and theircorresponding acrylates: ##STR11## the following allyl compound:##STR12##

Particularly preferred coupling compounds are the following methacrylatecompounds and their corresponding acrylates, wherein R and q are asdefined above. ##STR13##

The polymer of the present invention may optionally additionally containat least one silane moiety that is capable of undergoing a condensationreaction. A condensation reaction is the reaction of two molecules tocombine, with the elimination of a third compound. The third compoundmay be water or, depending on the structure of the specific reactants,this third compound may be an alcohol, amine or any other such compoundthat is eliminated in the reaction. This silane moiety may, for example,be provided at the time of manufacture of the polymer by coreaction ofthe A, B and C units described above with a D unit, which is derivedfrom an ethylenically unsaturated monomer copolymerizable with themonomers for A, B and C. This unit has a general formula

    X(Y).sub.n --Si(R.sup.12).sub.i T.sub.j

where

X is a vinyl group copolymerizable with the A and B monomers;

Y is a polyvalent linking group (e.g., alkylene, arylene, alkarylene,and aralkylene of 1 to 30 carbon atoms) optionally incorporatingheteroatoms e.g. O, N, S, P. Examples are ester, amide, urethane, ureagroups.

n is zero or 1;

R¹² is H or lower alkyl;

i is an integer from 0-2;

j is an integer from 1-3; and

i+j=3;

T is a hydroxy or a hydrolyzable group that includes halogen atoms,alkoxy, alkenoxy, acyloxy, carboxy, amino, amido, dialkyliminooxy,ketoxime, aldoxime, and similar groups. Preferably, the hydrolyzablegroup is selected from the group consisting of alkoxy, alkenoxy,acyloxy, ketoxime and aldoxime. More preferably, the hydrolyzable groupsare alkoxy groups such as methoxy and ethoxy, because of theircommercial availability, low cost and low toxicity. Examples of such Dunits include, but not limited to, acrylato- andmethacrylato-alkylalkoxysilanes as exemplified by the followingformulae. ##STR14## where, R¹³ is lower alkyl.

Vinylorganoalkoxysilanes such as vinyltrimethoxysilane,vinyltriethoxysilane and vinyl tris(2-methoxyethoxy)silane may also beused in some instances.

These D unit compounds can be used in their unhydrolyzed, partiallyhydrolyzed, or fully hydrolyzed form. In the latter two forms, andparticularly in the latter form, precautions must be taken to minimizethe formation of gels by silane dimerization and oligomerization throughsiloxane bonds. Any method for this known to those skilled in the artcan be used such as careful control of pH or capping of the hydroxylgroups to retard siloxane reactions.

The amount of the D unit silane compound used in the synthesis of thepolymer described above preferably is such that the silane moiety ispresent in 0.1-30 mole percent of the polymer. More preferably, thesilane moiety is present in 0.1-20 mole percent of the polymer, and mostpreferably in 0.1-10 mole percent of the polymer.

Copolymers containing a D unit as described above may be convenientlyprepared by copolymerizing the starting monomer units A, B, C and D bystandard vinyl polymerization techniques. Alternatively it is possibleto modify a fraction of the polar groups of A of a prepared polymer witha compound having at least one silane moiety that is capable ofundergoing a condensation reaction, which additionally has a groupcapable of reacting with the polar group of A.

Preferably, the coating composition contains three components. ComponentI is the copolymer containing a silane moiety that is capable ofundergoing a condensation reaction as described above. Component II is amaterial having at least two condensation silicone reaction sites thatare capable of undergoing a condensation reaction. Component III isoptional catalyst to promote the condensation reaction between polymersof Component I and/or between polymers of Component I and compounds ofComponent II.

Component II is a compound having at least two condensation siliconereaction sites that are capable of undergoing a condensation reaction,and therefore acts as a bridging compound between polymers of ComponentI in the present system. This component may optionally be acomparatively small molecule, or may be polymeric in nature. Preferably,Component II has a weight average molecular weight between about64-3000.

Examples of Component II include tetraethyl orthosilicate, and itspartially or fully hydrolyzed forms. Preferably, Component II isdescribed by the formula

    Y-- Si (R.sup.12).sub.i T.sub.j !.sub.k

where

Y is a polyvalent linking group (e.g., alkylene, arylene, alkarylene,and aralkylene of 1 to 30 carbon atoms) and optionally incorporatingheteroatoms e.g. O, N, S, P. Examples are ester, amide, urethane, ureagroups.

R¹² is H or lower alkyl

i is an integer from 0-2

j is an integer from 1-3

i+j=3

k=2-50.

T is a hydroxy or a hydrolyzable group that includes halogen atoms,alkoxy, alkenoxy, acyloxy, carboxy, amino, amido, dialkyliminooxy,ketoxime, aldoxime, and similar groups. Preferably, the hydrolyzablegroup is selected from the group consisting of alkoxy, alkenoxy,acyloxy, ketoxime and aldoxime. More preferably, the hydrolyzable groupsare alkoxy groups such as methoxy and ethoxy, because of theircommercial availability, low cost and low toxicity.

Examples of Component II are as follows: ##STR15##

where R¹⁴ ═--(CH₂)₃ --Si(OCH₃)₃

Component III is a catalyst that promotes the condensation of the silanemoiety that is capable of undergoing a condensation reaction. Moisturegenerally favors such curing reactions. Any condensation siliconecatalysts can be used for this purpose.

Preferred curing catalysts for crosslinking the polymers of the presentcoatings include the organometallic catalysts containing metals of groupIII-A, IV-A, V-A, VI-A, VIII-A, I-B, II-B, III-B, IV-B and V-B. Alsopreferred are the organic amine and organic acid catalysts for thesilicone condensation reaction. Particularly preferred catalysts are tindioctoate, tin naphthenate, dibutyltin dilaurate, dibutyltin diacetate,dibutyltin dioxide, dibutyl tin dioctoate, zirconium chelates, aluminumchelates, aluminum titanates, titanium isopropoxide, triethylenediamine, p-toluene sulfonic acid, n-butyl phosphoric acid, and mixturesthereof.

The combination of components I and III only, in the absence of II, maybe sufficient to provide enough crosslinking for a particularapplication. On the other hand, in certain applications, it may besufficient to combine components I and II only, particularly whencomponent II is provided in a partially prehydrolyzed form. The speed ofcure of the desired application, as well as the actual moleculararchitecture of the polymer of Component I and the bridging compound ofComponent II, will dictate the choice of a particular combination of thecomponents of this invention. By judicious choice of solvents andpackaging material and delivery system, it is possible to have aone-part or a multi-part system. In the latter case the multiple partscan be mixed just prior to application or can be applied as successivelayers.

Polymers containing a silane moiety that is capable of undergoing acondensation reaction may be applied in the same manner as otherpolymers as described above. For example, these polymers may be appliedto a surface of an article before insertion into the mouth, or may bepolymerized in situ in the mouth on the oral surface. Coatings mayadditionally be treated with a surfactant-containing composition foradditional benefit.

Coating of surfaces with compositions described herein after placementof orthodontic devices is particularly of interest. Protection of toothsurfaces adjacent to bonded brackets and the like is quite importantbecause good oral hygiene is difficult and the orthodontic devicesthemselves provide interstices for bacteria, etc. to gather. Animportant method of use of the present coating materials is applicationafter bonding of orthodontic devices to both the device itself and thetooth surface adjacent to the device.

In the method of the present invention, it is desirable to pretreat theoral surface to be coated with an acid before application of the coatingcomposition. Suitable acids include citric acid, maleic acid, nitricacid, oxalic acid, the acids of phosphorous, sulfur, boron, and thelike. Additionally, mildly acidic compositions such as those used toprovide fluoride treatments may also be used with benefit as a oralsurface pretreatment composition for surface preparation.

When the copolymer is applied as a coating it is generally useful todeliver it in combination with a carrier solvent. This carrier solventis then removed by suitable means e.g. drying. Examples of carriersolvents include water, ethanol, isopropanol, acetone silicone fluidssuch as D₄, and mixtures thereof. The coating can also be applied in theform of emulsion, e.g. oil-in-water or water-in-oil.

The coatings and surfactant treatments of this invention can be appliedas an oral rinse or as a professionally applied coating that can beoptionally fixed by further polymerization or cross-linking throughethylenic unsaturations present in the modulating group. The ingredientsmay also be incorporated into dentrifices such as toothpaste, dentalgel, toothpowder, chewing gum, lozenges etc. The coatings and treatmentsmay alternatively be part of a prophy paste or polishing paste that isthen applied during a finishing or polishing process with prophy cup,angle, disc etc. They may also be applied by a floss for delivery tointerproximal and other difficult to access areas.

For mouthwashes and mouthrinses, the liquid medium which acts as thecarrier for the polymer or surfactant may be aqueous or aqueousalcoholic solutions, and optionally may contain other inorganicsolvents. A surfactant such as a detergent may be present in polymerdelivery compositions.

Toothpastes, gels, chewing gum, lozenges and oral patches used fordelivery of either the polymer or the surfactant may additionallycontain humectants (such as glycerol, sorbitol, and polyethyleneglycol), polishing agents (such as silica, calcium carbonate, andtricalcium phosphate), and thickeners (usually a natural or syntheticgum such as carrageenan, hydroxymethyl cellulose or a syntheticthickener such as fumed silica). A composition is defined to be a pastewhen the inelastic modulus (otherwise known as "loss modulus") is lessthan the elastic modulus of the composition. A composition is defined tobe a gel when the inelastic modulus is equal to the elastic modulus ofthe composition. The composition is considered to be "paintable" when itcan be applied to the intended substrate using brushes, sponges or othersimilar applicators conventionally used in the dental arts.

Compositions for delivery of the polymer or surfactant may additionallycontain other adjuvants, such as flavorants (both natural and synthetic,such as peppermint oil, menthol and sweeteners), coloring agents,viscosity modifiers, preservatives, antioxidants and antimicrobialagents (such as hydroquinone, BHT, ascorbic acid, p-hydroxybenzoic acid,alkyl esters, sodium sorbate and thymol), other anti-plaque additives(such as organophosphonates, triclosan and others such as thosedisclosed in U.S. Pat. No. 3,488,419), oral therapeutic agents (such asfluoride salts, chlorhexidine and allantoin), pigments and dyes andbuffers to control ionic strength.

The compositions for delivery of the polymer may optionally additionallycomprise an ethylenically unsaturated compound. Examples of preferredethylenically unsaturated compounds are 2,2-bis4-(2-hydroxy-3-methacryloxypropoxy)phenyl!propane ("BIS-GMA") and2-hydroxyethyl methacrylate ("HEMA").

Polymers described herein are useful not only for incorporation intotoothpastes and the like, but also may be used as external coatingcompositions for foreign devices to be placed temporarily or permanentlyin the mouth. For example, these coating compositions may be applied todental articles that are manufactured outside of the mouth andsubsequently placed in the mouth, such as orthodontic brackets, wires,bridges, crowns, dentures and the like. These compositions may beprovided either before insertion into the mouth or after insertion bythe dental practitioner or by the patient. When these coatingcompositions are applied to preexisting structure or man-made articlesin the mouth, the coating composition may be applied in the form of thepolymer or as precursors to the polymer which are in turn polymerizedextra-orally or intra-orally by thermal, photoinitiated or redoxpolymerization. The low frictional coefficients of restorative materialscoated by compositions containing these polymers improve the wearresistance of these restorations as compared to restoratives that do notcontain these polymers.

When the polymers of the present compositions comprise pendantethylenically unsaturated moieties that can be reacted in a subsequentstep after application to the intended substrate, the compositions alsocomprise a polymerization catalyst to effect reaction of theethylenically unsaturated group. Such catalyst may comprise aphotoinitiation catalyst or the combination of an oxidizing agent and areducing agent. Preferably, the initiation agent is appropriate fromsafety considerations for use in the human body.

The photoinitiator should be capable of promoting free radicalcrosslinking of the ethylenically unsaturated component on exposure tolight of a suitable wavelength and intensity. It also preferably issufficiently shelf-stable and free of undesirable coloration to permitits storage and use under typical dental conditions. Visible lightphotoinitiators are preferred. The photoinitiator frequently can be usedalone but typically it is used in combination with a suitable donorcompound or a suitable accelerator (for example, amines, peroxides,phosphorus compounds, ketones and alpha-diketone compounds).

Preferred visible light-induced initiators include camphorquinone (whichtypically is combined with a suitable hydrogen donor such as an amine),diaryliodonium simple or metal complex salts, chromophore-substitutedhalomethyl-s-triazines and halomethyl oxadiazoles. Particularlypreferred visible light-induced photoinitiators include combinations ofan alpha-diketone, e.g., camphorquinone, and a diaryliodonium salt,e.g., diphenyliodonium chloride, bromide, iodide or hexafluorophosphate,with or without additional hydrogen donors (such as sodium benzenesulfinate, amines and amine alcohols). Preferred ultravioletlight-induced polymerization initiators include ketones such as benzyland benzoin, and acyloins and acyloin ethers. Preferred commerciallyavailable ultraviolet light-induced polymerization initiators include2,2-dimethoxy-2-phenylacetophenone ("IRGACURE 651") and benzoin methylether (2-methoxy-2-phenylacetophenone), both from Ciba-Geigy Corp.

The photoinitiator should be present in an amount sufficient to providethe desired rate of photopolymerization. This amount will be dependentin part on the light source and the extinction coefficient of thephotoinitiator. Typically, the photoinitiator components will be presentat a total weight of about 0.01 to about 5%, more preferably from about0.1 to about 5%, based on the total weight (including water) of theunset coating components.

Alternative polymerization initiators include redox systems, which are acombination of a reducing agent and an oxidizing agent. These agentsshould react with or otherwise cooperate with one another to producefree-radicals capable of initiating polymerization of theethylenically-unsaturated moiety. The reducing agent and oxidizing agentpreferably are sufficiently shelf-stable and free of undesirablecolorization to permit their storage and use under typical dentalconditions. They should be sufficiently soluble in or miscible with thecarrier medium. The reducing agent and oxidizing agent should be presentin amounts sufficient to permit an adequate free-radical reaction rate.Useful reducing agent/oxidizing agent pairs are shown in "RedoxPolymerization", G. S. Misra and U. D. N. Bajpai, Prog. Polym. Sci., 8,61-131 (1982).

Preferred reducing agents include ascorbic acid, cobalt (II) chloride,ferrous chloride, ferrous sulfate, hydrazine, aromatic and aliphaticamines hydroxylamine (depending upon the choice of oxidizing agent)oxalic acid, thiourea, sulfuric acids and salts, and salts of adithionite or sulfite anion. Preferred oxidizing agents include cobalt(III) chloride, tert-butyl hydroperoxide, ferric chloride, hydroxylamine(depending upon the choice of reducing agent), perboric acid and itssalts, and salts of a permanganate or persulfate anion. Hydrogenperoxide can also be used, although it has been found to interfere withthe photoinitiator in some instances.

The amount of reducing agent and oxidizing agent should be sufficient toprovide the desired degree of polymerization of theethylenically-unsaturated component. The preferred amount for each ofthe reducing agent and oxidizing agent is about 0.01 to about 10%, morepreferably about 0.02 to about 5%, based on the total weight (includingwater) of the components. Surfactant treatment, esp. neutral andcationic.

For crosslinkable polymers that are polymerized by a cationic mechanism,suitable intitators include salts that are capable of generating cationssuch as the diaryliodonium, triarylsulfonium and aryldiazonium salts.

As noted above, it has surprisingly been found that post-treatment ofthe coatings described herein by a surfactant containing compositionprovide excellent reduction of adhesion for bacteria or proteinaceousmaterials. The surfactants may be incorporated at very small amounts inthe post-coating composition, and may be either non-ionic or ionicsurfactants. Particularly preferred surfactants for use in thepost-coating treatment are non-ionic surfactants.

The preferred ionic surfactants include the salts of long-chainedaliphatic acids such as sodium dodecylsulfate or sodium octadecylsulfate. Optionally, the polymer of the coating may contain ionicfunctionality that acts as the counterion to the surfactant.

The preferred non-ionic surfactants are based on polyhydroxy esters oflong chain fatty acids, or polyhydroxy ethers of long chain fattyalcohols. Particularly preferred are polyoxyethylene, sorbitan ethers oflong chain fatty acids, e.g. Tween™ 20, 40, 60, or 80 surfactants.

Coatings as described herein may additionally be useful for coatingmedical articles and articles for use in the medical environment thatwould benefit from reduced adhesion to surfaces thereof. Examples ofsuch medical articles include devices that are temporarily orpermanently implanted in the body, such as pacemakers, blood vesselsieves, bone repair and replacement materials, and the like. Articlesthat come into contact with body fluids, such as catheters and surgicalinstruments, also may benefit from being provided with the coating ofthe present invention. Additionally, articles used for infection controlpurposes, such as gloves, masks, gowns, drapes and the like, may alsobenefit from the present coatings.

Substantivity of the coatings of the present invention may be measuredby a number of techniques. For example, one may evaluate by chemicalmeans whether or not a coating remains after other types of assault onthe coatings. One such analytical means is evaluation of the advancingcontact angle using a Wilhelmy Balance as described herein. Preferably,the contact angle is greater than 55° measured against water.

Alternatively, the continued effectiveness of the coating may beevaluated by determining resistance to stain or resistance to bacterialadhesion of a substrate. Resistance of the coating may be evaluated byusing a physical assault or a soak assault on the coating. The physicalassault may be provided by scrubbing with a brush having a predeterminedload for limited periods of time. Alternatively, a physical assault maybe provided by repititious grinding or polishing of teeth under amechanical mechanism used to simulate the action of teeth in the mouth.

Wilhelmy Balance

To evaluate the hydrophobicity and hydrophilicity of the coatings of thepresent invention, the well-known Wilhelmy Balance technique is used tomeasure the advancing and receding water contact angles, respectively.This technique is discussed, for example, in "Wettability," John C.Berg, editor, Marcel Dekker, Inc., New York, 1993, pp 11-25. Measurementis taken on a continuous coated sample. All contact angle measurementsare done with water.

Preferably, the coatings of the present invention are sufficientlysubstantive to the intended substrate to provide a water advancingcontact angle of at least 55° as measured using the Wilhelmy Balance asdescribed herein for a sample that has been subjected to 2 weeks ofsoaking in distilled water at 37° C. More preferably, an advancingcontact angle of at least 55° is provided on a sample that has been sosoaked for three months.

The following examples are given to illustrate, but not limit, the scopeof this invention. Unless otherwise indicated, all parts and percentagesare by weight, and all molecular weights are weight average molecularweight.

EXAMPLE 1

Iso-butylmethacrylate (14 g), acrylic acid (2 g), ethylenicallyunsaturated silicone macromer of molecular weight 10,000 preparedaccording to the procedure for making "monomer C 3b" at column 16 ofU.S. Pat. No. 4,693,935 ("PDMS macromer") (4 g) andazobisisobutyronitrile ("AIBN", 0.1 g) were dissolved in iso-propanol.After deoxygenating, the solution was allowed to polymerize at 55° C.The polymer was designated as P1. The solution was then independentlycoated on etched enamel and dentin. Contact angles were measured by theWilhelmy balance method using a DCA 322 contact angle analyzer obtainedfrom ATI Instrument, Madison, Wis. Up to 3 cycles were used. Results areshown below:

                  TABLE 1    ______________________________________    Contact Angles                   Cycle 1 Cycle 2 Cycle 3    ______________________________________    Control bare etched.sup.1 enamel,    polished    Advancing        59        45      41    Receding         1.8       1.1     5.1    Etched enamel, polished, P1    coated    Advancing        107       107     106    Receding         71        69      67    Above coated enamel slab    etched with phosphoric acid    Advancing        105       106     105    Receding         67        66      66    Above coated enamel slab    polished (super fine Sof-lex    disk ™).sup.2    Advancing        104       104     102    Receding         57        55      53    ______________________________________     .sup.1 Etched with 35% phosphoric acid gel.     .sup.2 Soflex polishing disk (3M).

                  TABLE 2    ______________________________________    Contact Angles                   Cycle 1 Cycle 2 Cycle    ______________________________________    Control bare etched enamel    advancing        19        33      34    receding         30        38      39    advancing        35        35      36    receding         39        40      40    enamel from above etched,    P1 coated    advancing        103       102     102    receding         67        64      63    enamel from above wiped    with methyl alcohol, etched    advancing        89        88      --    receding         35        35      --    enamel from above polished    (fine Sof-lex), etched    advancing        80        --      --    receding         42        --      --    enamel from above polished    (medium Sof-lex disk ™),    etched    advancing        43        34      32    receding         25        26      26    ______________________________________

From the above results it is apparent that the coating of the polymer P1on enamel makes the surface hydrophobic. The coating is not easily lostas noted by the advancing contact angle remaining quite high even afteragressive treatments. It is only when it is mechanically abraded awaywith coarser grades of abrasives that it begins to wear away.

Similar studies were performed after coating a dentin slab with thepolymer P1. Results are shown below in table 3.

                  TABLE 3    ______________________________________             Trial 1       Trial 2             Cycle         Cycle   Cycle                                        Cycle Cycle             1     Cycle 2 3       1    2     3    ______________________________________    etched bare dentin    advancing  92      40      40    37   20    25    receding   8.7     8.3     7.4   20   25    28    above sample    etched, polished    advancing  112     108     108   106  98    98    receding   65      66      66    39   40    40    above coated slab    etched with    phosphoric acid    advancing  101     101     100   101  100   70    receding   54      52      49    46   45    44    above coated slab    then polished (Sof-    lex disk ™)    advancing  77      60      59    101  100   70    receding   29      28      27    46   45    44    ______________________________________

EXAMPLE 2

Iso-butylmethacrylate (13 g), acrylic acid (3 g), PDMS macromer (4 g)and AIBN (0.1 g) were dissolved in THF. After deoxygenating the solutionwas allowed to polymerize at 55° C. About one-third portion of thecarboxylate groups of the resultant polymer were derivatized withisocyanatoethyl methacrylate to provide pendant unsaturated groups. THFwas then exchanged with 60 g isopropanol. To a 10 g portion of thissolution were added 0.0123 g diphenyliodonium hexafluorophosphate and0.0031 g of camphorquinone. This polymer is designated as P2. Thecoating prepared from the polymer was further crosslinked by irradiationwith visible light source, Visilux™ 2 from 3M Company.

Results of contact angle study by Wilhelmy balance method are shown inTable 4 below:

                  TABLE 4    ______________________________________                Cycle 1  Cycle 2 Cycle 3    ______________________________________    Etched bare enamel    advancing     28         38      39    receding      39         41      42    Etched enamel coated    with P2    advancing     103        99      99    receding      22         17      18    Etched bare dentin    advancing     54         36      36    receding      36         38      38    Etched dentin coated    with P2    advancing     112        99      97    receding      61         60      59    ______________________________________

The advancing contact angle results show that after treatment with thepolymer P2 the hydrophobicity of both the enamel and dentin surfacesincreases significantly.

Slabs of Z100 dental composite were coated with P1 or P2. Coating P2 wasfurther crosslinked as described earlier. Contact angles were thenmeasured. The results are given in Table 5 below:

                  TABLE 5    ______________________________________                Cycle 1  Cycle 2 Cycle 3    ______________________________________    Bare Z100, etched    (slab 2) advancing                  63         65      64    receding      28         28      28    (slab 4) advancing                  61         64      63    receding      36         35      35    Etched, P1 coated    (slab 2) advancing                  107        106     106    receding      68         69      69    Etched, P2 coated    (slab 4)      106        106     106    receding      67         67      68    Bare, etched, polished    Z100 slab    (slab 1) advancing                  53         52      51    receding      14         14      14    (slab 3) advancing                  50         46      48    receding      22         22      23    etched, polished Z100    PI coated    (slab 1) advancing                  106        107     107    receding      68         70      71    etched, polished Z100    P2 coated    (slab 3) advancing                  105        104     103    receding      66         65      66    ______________________________________

EXAMPLE 3

Ethyl methacrylate (11.4 g), acrylic acid (2 g), PDMS macromer (4 g) andAIBN (0.1 g) were dissolved in 75 ml of absolute ethanol. The reactionmixture was flushed with nitrogen for 15 minutes and then heated at 55°C. for 8 hours. It was then allowed to cool to room temperature anddiluted with an equal volume of isopropanol. This polymer solution wasdesignated as P3.

A slab of bovine enamel was polished with abrasive paper and its contactangle determined in water using the Wilhelmy balance method. The slabwas then dried, coated with the solution of P3, air dried, and itscontact angle determined again. The values of the-control uncoatedenamel as well as the coated enamel are shown in Table 6. The experimentwas repeated with a slab of bovine dentin; its results are shown inTable 7. A slab of cured Vitremer™ tri-cure glass ionomer was preparedand similarly treated. Results of contact angle on this material beforeand after coating are shown in Table 8.

                  TABLE 6    ______________________________________    Substrate      Contact Angle    ______________________________________    Bare, polished enamel                   Cycle 1    Cycle 2 Cycle 3    Advancing      68         35      35    Receding       38         39      39    Polished enamel with P3                   Cycle 1    Cycle 2 Cycle 3    Advancing      99         98      97    Receding       59         54      52    ______________________________________

                  TABLE 7    ______________________________________    Substrate     Contact Angle    ______________________________________    Bare dentin   Cycle 1    Cycle 2 Cycle 3    Advancing     77         33      34    Receding      34         34      34    Dentin coated with P3                  Cycle 1    Cycle 2 Cycle 3    Advancing     103        102     94    Receding      62         55      53    ______________________________________

                  TABLE 8    ______________________________________    Substrate           Contact Angle    ______________________________________    Vitremer control slab                        Cycle 1 Cycle 2    Advancing           70      90    Receding            28      27    Vitremer slab coated with P3                        Cycle 1 Cycle 2    Advancing           108     108    Receding            68      67    ______________________________________

From the above data it is apparent that coating with the polymer P3solution increases the hydrophobicity of the surfaces and that thecoating is also retentive.

EXAMPLE 4

Synthesis of polymers A-F

Reagents, as specified in Table 9 were charged into a 3-necked 250 mlround bottom flask fitted with a nitrogen inlet tube, condenser andthermometer. A magnetic stirring bar was placed in the flask and thereagents stirred for 15 minutes with dry nitrogen bubbling brisklythrough the homogeneous solution. After 15 minutes, the nitrogen flowwas reduced and switched from bubbling to blanketing conditions. Thesolution was heated at 60° C. with stirring, using an oil bath equippedwith an electronic temperature controller. Heating was continued for 8hours. The reaction mixture was then precipitated into water, using 5 mlof water for every ml of polymer solution. The white polymer precipitatewas then collected by precipitation, washed with cold water and thendried in a vacuum oven at 70° for several days.

                  TABLE 9    ______________________________________          acrylic isobutyl-   PDMS     AIBN    polymer          acid (g)                  methacrylate (g)                              macromer (g)                                       (g)   THF ml    ______________________________________    A     1.01    15.0        2.0      0.1   54    B     3.02    13.0        2.0      0.1   54    C     2.02    14.0        4.0      0.1   60    D     1.02    15.0        6.0      0.1   66    E     3.01    13.0        6.0      0.1   66    F     4.00    14.0        2.0      0.1   60    ______________________________________

Enamel slab

The labial surface of extracted bovine tooth was ground flat with 120grit abrasive paper to expose a clean dentin surface free from enamel.This was then polished with 600 grit paper to provide a smooth surface.Using a diamond saw, a thin wafer (about 1/2 mm) was cut off to includethe polished surface. Two such wafers were then glued together withScotchbond™ Multipurpose (SBMP) dental adhesive system (3M) so that thepolished surfaces were facing outwards. The glued sandwich was then cutto give a rectangle of dimensions of about 8 mm×6 mm. A small flatbutton of a dental composite material was then attached to one of theshort sides of the enamel sandwich to provide a handle, using SBMPdental adhesive.

Dentin Slab

The labial surface of a bovine tooth was ground flat with 120 gritabrasive paper to expose a large area of dentin. Using a diamond saw athin flat slab was sectioned off parallel to the ground surface. Thethickness of the slab was about 1 mm. Care was taken to see that the cutsurface was dentin only (no visible sign of pulp chamber). The dentinslab was then polished on both flat surfaces with 600 grit paper. A 6mm×8 mm rectangular section was then cut out with a diamond saw. A smallflat button of composite was then glued on to one end (short side) withSBMP.

EXAMPLE 5

Bare enamel slab was first etched with 35% phosphoric acid gel and thenpolished with 600 grit sand paper. The uncoated slab was tested forcontact in water. The slab was then coated with a solution (7.5% polymerin isopropanol) of one of the polymers A-F by dipping for 5 minutes,blotting, followed by air drying. The slab of enamel, coated withpolymer was tested for advancing contact angle in water using theWilhelmy Balance. The coated enamel sample was then stored in deionizedwater for 2 days and tested again. The sample was then incubated inpooled saliva for 90 minutes, blotted dry and then tested for contactangle. The above sample was then stored in water for 10 minutes andretested. The washed slab, after retesting, was then brushed with amedium bristle tooth brush and then retested for contact angle. Theresults of advancing contact angle values are shown in Table 10.Advancing contact angle values at the third cycle are reported since atthis time equilibrium is attained.

                  TABLE 10    ______________________________________               Adv. contact Angle after third cycle                     polymer polymer                                   polymer                                         polymer                                               polymer    STEP             B       C     E     F     A    ______________________________________    1    Bare enamel etch,                     34      25    28     5    18         polish    2    polymer coated                     77      89    77    75    75         after step 1    3    water stored after                     69      94    74    76    73         step 2    4    saliva incubated                     25      83     0    58    27         after step 3    5    water stored after                     24      83    51    70     0         step 4    6    brushed after step                     70      83    62    84    68         5    ______________________________________

The above results indicate that after coating the enamel the toothsurface becomes hydrophobic. The storage in water does not substantiallydecrease the contact angle, which means the coating is substantive atthis point. After incubation with saliva, the salivary proteins andother components stick to some extent on coated surfaces obtained frompolymers A, B and E. The saliva treated surface from those polymers aretherefore hydrophilic because of adhered proteins and other salivarycomponents. When the saliva treated surface is washed with water (step5) some of the adherent species from saliva are washed off the surfaceproduced from polymer E. On toothbrushing (step 6), most of the salivarycomponents are removed and the hydrophobic polymer surfaces arere-exposed as manifested by the higher contact angle readings (close tooriginal coated samples). For teeth coated with polymers C and F, notmuch decrease in contact angle is seen even initially after salivaincubation, thus indicating that adhesion was not favorable to thesesubstrates.

EXAMPLE 6

To show substantivity of coatings, cut enamel or dentin slabs (having noother treatment) were first evaluated for contact angle. These were thenindependently coated with a solution of polymers B and C at 7.5%concentration by weight as indicated in Table 11 and 12 and dried.

The coated samples were stored for 18 hours in distilled water at 37°C., blotted dry and contact angles were determined. These values areshown in Table 11 and 12.

The samples were then immersed in water and incubated at 37° C. for 1week and contact angles were determined. These values are shown in Table11. The contact angle determination was repeated after 2 weeks ofincubation, and then again after 3 months of incubation.

Samples were done in replicate. Average of advancing contact angle ofthe two polymers at the second cycle is reported in Table 11 and Table12.

                  TABLE 11    ______________________________________           Avg. of second cycle adv. contact angle    ENAMEL   Initial*  18 h.sup.1                              1 wk.sup.1                                     2 wk.sup.1                                          3 mos.    ______________________________________    polymer B             45        102    95     89   82    polymer C             52        103    97     83   88    ______________________________________     *Initial is uncoated substrate     .sup.1 Time of soaking in water at 37° C.

                  TABLE 12    ______________________________________    DENTIN          Initial*                            18 h.sup.1                                     1 wk.sup.1                                          2 wk.sup.1    ______________________________________    polymer B       37      103      95   90    polymer C (one sample)                    37      105      99   89    ______________________________________     *Initial is uncoated substrate     .sup.1 Time of soaking in water at 37° C.

EXAMPLE 7

Effect of pretreatment of enamel or dentin.

The cut and polished enamel or dentin slabs were either (a) etched for15 seconds with phosphoric acid gel and rinsed with water and driedprior to application of polymer coating or (b) pumiced with Nupro™coarse polishing paste enamel slabs polished for 10 min. per side,dentin slabs 4 min. per side!, rinsed thoroughly with water and contactangle determined.

The slabs were then coated with polymer C and contact angles determinedafter 18 h, 1 week and 2 week storage in distilled water at 37° C.

The advancing angle after the second cycle for these experiments arereported in Table 13 and shows that substantivity of the coating ismaintained even after prolonged storage.

                  TABLE 13    ______________________________________             Initial (uncoated             enamel or dentin)                        18 h*   1 wk*   2 wk*    ______________________________________    Enamel acid etched               48           103     85    83    Enamel pumiced               34           103     90    79    Dentin acid etched               22            95     85    67    Dentin pumiced               40           103     92    82    ______________________________________     *Time of soaking of coated tooth slab in water at 37° C.

COMPARATIVE EXAMPLE 1

Polydimethylsiloxane polymers containing dimethylpropylamino groups wereevaluated for substantivity and hydrophobicity. Two such commerciallyavailable polymers were used: PS 510 (molecular weight 2,500) and PS 513(molecular weight(27,000) from Petrach, Huls.

A 7.5% solution of PS 510 was prepared in acetone. Enamel slabs werecoated with this solution followed by drying. Contact angles were thendetermined.

                  TABLE 14    ______________________________________                              Adv. Contact angle at    Step  Sample              2nd Cycle    ______________________________________    1     Cut polished enamel 51    2     Coated after step 1 93    3     Tooth-brushed after step 2                              72    4     Aged in water 2 weeks after step 3                              48    ______________________________________

The decrease in contact angle indicates that the coating was notsubstantive because hydrophobicity was lost.

COMPARATIVE EXAMPLE 2

Dentin slabs, after cutting and polishing, were coated with a solutionof PS 510 (7.5% in acetone) or PS 513 (7.5% in methylethyl ketone). Thecoated samples were measured for contact angle. These were then aged at37° C. and the contact angle was measured again. Measurement values arereported in Table 15.

                  TABLE 15    ______________________________________    contact initial  coated, then                               coated, then                                        coated, then    angle (2nd            (prior to                     18 h in water                               1 wk in water                                        2 wk in water    advancing)            coating) @ 37° C.                               @ 37° C.                                        @ 37° C.    ______________________________________    PS 510  36       85        84       41    PS 513  47       87        65       34    ______________________________________

Loss in contact angle indicates that the coatings were not substantive.

To further evaluate the efficiency of the present coatings, moredetailed analysis using biological methodologies were carried out.Biological evaluation generally methods and materials.

Enamel Particles

Enamel particles were produced from approximately 100 bovine teeth byfirst removing all adherent tissue by scraping with a scapel and adental curette. The roots were removed with a cutting wheel at thecemento-enamel junction and the pulp removed. The crowns were thenimmersed in liquid nitrogen for 20 minutes, removed and immediatelytapped with a hammer. The dentin was removed from the largest pieceswith a grinding wheel. The enamel slabs were then placed in ananalytical mill and treated for about 5 minutes at 40° C. The resultantpowder was sieved to obtain particles of about 80-120 uM. The particleswere washed, treated with acid to clean them and stored dry at 40° C.until used.

Collection/Processing of Saliva Pool

Saliva was collected from volunteers who were asked to chew a 2 inchsquare of Parafilm for 2-3 minutes and expectorate into a chilled 50 mltube. The samples were then pooled and centrifuged at 10,000 rpm for 20minutes at 4° C. The clarified saliva was aliquoted into 10 ml vials andstored at -70° C. until just prior to use.

BIOLOGICAL EVALUATION 1 OF COATINGS

Samples of powdered enamel coated with four polymers were prepared usingthe polymers A, B, C and E.

These samples were provided for a biological adherence test. Initially,the coated particles were challenged with three materials:

IgG--Immunoglobulin protein PI 7.5

OVA--Ovalbumin protein PI 3.5

P.gin--P-gingivalis bacteria.

Materials and Methods

Fluorescent Labeling of Bacteria.

Ten ml of P.gingivalis bacteria at 10⁹ /ml in Phosphate Buffered Saline(PBS) were combined with 0.1 ml of Fluorescein Isothiocyanate (FITC) at1 mg/ml in PBS. The mixture was rotated at room temperature for 1 hourand then washed with 40 ml portions of PBS until the optical density ofthe supernatant at 495 nm was zero. The dyed bacterial pellet was thenresuspended in 10 ml of PBS with 0.1% sodium azide and stored at 4° C.until used.

Coating of Enamel Particles.

One hundred and fifty mg of particles (either coated with polymer ornot) were combined with 2.5 of human saliva and rotated at roomtemperature in polypropylene tubes for 1-2 hours. Uncoated particleswere rotated at the same time in PBS as controls. The particles werethen washed in PBS three times to remove unbound saliva and adjusted to100 mg/ml in PBS and stored at 4° C. until used.

Adherence Assay.

Five mg of particles (in triplicate) were pipetted into the wells of aconical bottom microfilter plate (NUNC) and washed three times with 200ul of PBS. One hundred ml of either FITC-labeled bacteria, IgG orovalbumin was added to each well and the plate incubated at roomtemperature with constant shaking for one hour. The wells were thenwashed 3 times with 250 ul of PBS and resuspended in 250 ul of the samebuffer. Twenty ul portions of the particles were removed and placed inthe wells of a IDEXX Assay Plate with a glass fiber filter bottom. Theplates were then placed in an IDEXX Screen Machine™, the liquid removedby vacuum filtration and the bound fluorescence determined. After theinitial reading the plates were washed twice with PBS containing 0.125%NP-40 and the bound fluorescence redetermined in the Screen Machine™.Results were expressed as relative fluorescent units (RFU).

Results.

Particles were tested both with and without polymer coating. Half ofeach were treated in pooled saliva. These saliva treated particles werethen washed with phosphate buffered saline (PBS) and tested foradherence with the non-saliva treated particles. The bound fluorescencewas calculated as the percentage of the positive control, i.e. thebinding of the bacteria or protein to uncoated enamel particles. Theparticles were also washed with PBS containing 0.125% NP-40 andbacterial and protein adherence measured.

Results in FIG. 3 are particles rinsed with PBS, those in FIG. 4 are forparticles rinsed in PBS+NP-40. Uncoated enamel absorbed large amounts ofall three test biologicals (this is 100% on relative scale); coating theenamel with saliva reduced that binding somewhat for IgG but not for OVAand P.gin. Coating the particles with polymer reduced bindingsubstantially, however polymer coated particles supercoated with salivatended to regain some absorptive properties. Coated particles treatedwith saliva, then biologicals and washed briefly with PBS containing thenon-ionic detergent NP-40 showed substantial decrease of adherence ofIgG and OVA for all coatings and P.gin.

BIOLOGICAL EVALUATION 2 OF COATINGS

Growth of Bacterial Strains

Mutans streptococci strains were obtained from the University ofMinnesota Dental School (strains 43-2, 43-3 and RL19) as fresh isolatesfrom persons seeking dental care. Additional Mutans streptococci strainswere obtained from the American Type Culture Collection (Strains 10558,12396, 27351, 27352, 27609 and 33399). All strains were grown in ToddHewitt Broth in an anaerobic chamber at 37° C. Cells were harvested inlate log growth phase and washed three times in sterile filtered saline.The cells were then resuspended at an optical density ("OD") of 1.0 (600nm) in sterile filtered KCl buffer (0.1M NaCl, 0.05M KCl, 0.1M MgCl₂ 0.1mM potassium phosphate and 1 mM CaCl₂, pH 7.0).

Production of Whole Genomic Probes

DNA was isolated from the bacteria using an ASAP™ Kit (BoeringerManheim) according to the manufacturers directions. Briefly, about 10⁹cells of the various strains were combined with 2 ml of lysis buffersupplemented with 1 mg/ml Mutanolysin (Sigma). Sixty microliters of heattreated RNAse and 160 μl of lysozyme solution were then added and mixedby gentle inversion. The suspended cells were then incubated at 37° C.for 30 minutes and 100 μl of Proteinase K added. After mixing by gentleinversion, the suspended cells were incubated for 60 minutes at 60° C.Four mililiters of binding buffer was added, mixed by gentle inversionand the entire sample added to a column of DNA binding matrix. Thecolumn was drained by gravity and an additional 3 ml of binding bufferadded and redrained. One-half milliliter of primary elution buffer wasadded and the column drained to elute RNA and protein followed by 2 mlof DNA elution buffer which was collected in a 10 mm×100 mm tube. TheDNA was then precipated with isopropanol, washed with ethanol and dried.The resultant pellet of DNA was then dissolved in 50 μl of Tris-EDTA("TE") buffer and the amount and purity of each preparation determinedby optical density at 260/280 nm and electrophoresis on 0.85% TE.

DNA was labeled by nick translation using a GENIUS™ Non-radioactive DNALabeling Kit (Boeringer Manheim) according to the manufacturersdirections. Briefly, 4.5 ug of DNA from each bacterial strain wascombined with a balanced mix of hexanucleotides, dNTPs labeled withdegoxigenein, the Klenow enzyme and water to 20 ul. The tubes werecentrifuged for 10 seconds and incubated overnight at 37° C.

Dot Blot Assays for Adherent Bacteria

Coated and uncoated enamel particles were independently added to 1 ml ofsaliva and rotated at room temperature for 1 hour. The particles werewashed with buffered KCl and 1 ml of bacteria at OD 1.0 (600 nm) addedand the mixture rotated at room temperature for an additional hour. Theparticles were then washed in one of 5 buffer solutions (see below). Theparticles were then pelleted, 50 μl of DNA extraction buffer added andthe suspended particles boiled to extract and solubilize the DNA. Theparticles were cooled quickly to 40° C., centrifuged and replicatesamples of 10 μl for each tube dotted onto a Zeta-Probe™ membrane(BioRad). The membranes were then treated with pre-hybridization solutionwashed and 100 ng of nick translated DNA Probe added in 25 ml ofhybridization solution. The hybridization was allowed to incubate at 65°C. overnight before washing three times to remove the unbound probe. Themembranes were then incubated in milk blocking solution for 1 hour andgoat anti-digoxegenin (1:1000 in blocking buffer) added. After anadditional incubation of 1 hour, the membranes were washed to removeunbound antibody and submerged in enzyme substrate solution for 1-2hours. The reactions were stopped by washing the membrane in EDTAsolution and the intensity of the dots estimated by a single observer,using the following scale:

0=no color,

1=just visible,

2=clearly visible circle

3=clearly visible dark circle

4=very dark, highest intensity circle

Washing Experiments to Estimate Strength of Adherence

Five different buffers were prepared for washing experiments: BufferedKCl, Buffered KCl+1% Tween 20, Buffered KCl+1% Tween 80, Buffered KCl+1%soluble toothpaste extract and Buffered KCl+1% mouthwash. Each bufferwas used individually as the final wash for the microbial adherenceexperiments.

Microbial Adherence Experiments

The adherence values for the various combinations of bacteria, plaqueresistant coatings and controls can be seen in Table 16. In general,there was an overall reduction of binding of about 25% (range=10-47%)when the enamel coated with all experimental materials were tested andcompared to controls in the KCl buffer. Also, there was a substantialreduction, ranging from 81-29%, of binding to the coated particles whenthe various surfactants or oral products were added to the wash buffer,as compared to untreated enamel controls and a reduction of 86-13%compared to the saliva treated controls. This reduction was greater thancan be accounted for by the addition of the various wash solutionsalone.

                                      TABLE 16    __________________________________________________________________________    Bacterial          ENAMEL TREATMENT    Strains          E + B + KCL                 E + S + KCL                        A1 + S + KCL                               B1 + S + KCL                                      C1 + S + KCL                                             E1 + S + KCL    __________________________________________________________________________    43-3  2.00   1.00   2.00   1.00   1.00   0.00    43-2  2.00   3.00   3.00   3.00   2.00   2.00    RL-19 1.00   1.00   0.00   0.00   0.00   0.00    10558-432          3.00   3.00   2.00   2.00   3.00   3.00    12396-433          3.00   2.00   1.00   1.00   2.00   3.00    27351 2.00   3.00   0.00   3.00   3.00   2.00    27352 1.00   1.00   2.00   3.00   3.00   3.00    27609-new          2.00   1.00   0.00   0.00   0.00   0.00    33399 3.00   1.00   0.00   3.00   3.00   0.00    Average          2.11   1.78   1.11   1.78   1.89   1.44    Standard          0.78   0.97   1.17   1.30   1.27   1.42    Deviation    __________________________________________________________________________    Bacterial          ENAMEL TREATMENT    Strains          E + B + T20                 E + S + T20                        A1 + S + T20                               B1 + S + T20                                      C1 + S + T20                                             E1 + S + T20    __________________________________________________________________________    43-3  1.00   2.00   0.00   0.00   0.00   0.00    43-2  3.00   2.00   1.00   0.00   0.00   2.00    RL-19 0.00   0.00   0.00   0.00   0.00   1.00    10558-432          2.00   2.00   0.00   0.00   2.00   2.00    12396-433          1.00   0.00   1.00   0.00   0.00   0.00    27351 0.00   0.00   0.00   0.00   0.00   0.00    27352 0.00   0.00   0.00   0.00   0.00   0.00    27609-new          0.00   0.00   0.00   0.00   0.00   0.00    33399 0.00   0.00   3.00   0.00   0.00   3.00    Average          0.78   0.67   0.56   0.00   0.22   0.89    Standard          1.09   1.00   1.01   0.00   0.67   1.17    Deviation    __________________________________________________________________________    Bacterial          ENAMEL TREATMENT    Strains          E + B + T80                 E + S + T80                        A1 + S + T80                               B1 + S + T80                                      C1 + S + T80                                             E1 + S + T80    __________________________________________________________________________    43-3  1.00   3.00   0.00   0.00   0.00   0.00    43-2  2.00   3.00   0.00   0.00   0.00   2.00    RL-19 1.00   0.00   0.00   0.00   3.00   0.00    10558-432          3.00   3.00   0.00   0.00   3.00   3.00    12396-433          3.00   3.00   0.00   0.00   0.00   0.00    27351 1.00   0.00   0.00   0.00   0.00   0.00    27352 0.00   0.00   0.00   0.00   0.00   0.00    27609-new          0.00   2.00   0.00   0.00   0.00   1.00    33399 0.00   0.00   0.00   3.00   0.00   0.00    Average          1.22   1.56   0.00   0.33   0.67   0.67    Standard          1.20   1.51   0.00   1.00   1.32   1.12    Deviation    __________________________________________________________________________    Bacterial          ENAMEL TREATMENT    Strains          E + B + TP                 E + S + TP                        A1 + S + TP                               B1 + S + TP                                      C1 + S + TP                                             E1 + S + TP    __________________________________________________________________________    43-3  1.00   1.00   0.00   0.00   0.00   0.00    43-2  3.00   3.00   0.00   0.00   0.00   0.00    RL-19 2.00   2.00   3.00   3.00   0.00   2.00    10558-432          0.00   0.00   0.00   3.00   0.00   0.00    12396-433          3.00   3.00   3.00   3.00   3.00   3.00    27351 3.00   3.00   0.00   4.00   0.00   3.00    27352 0.00   0.00   0.00   0.00   0.00   3.00    27609-new          2.00   3.00   0.00   0.00   0.00   3.00    33399 3.00   3.00   3.00   3.00   3.00   3.00    Average          1.89   2.00   1.00   1.78   0.67   1.89    Standard          1.27   1.32   1.50   1.72   1.32   1.45    Deviation    __________________________________________________________________________    Bacterial          ENAMEL TREATMENT    Strains          E + B + MW                 E + S + MW                        A1 + S + MW                               B1 + S + MW                                      C1 + S + MW                                             E1 + S + MW    __________________________________________________________________________    43-3  0.00   2.00   0.00   0.00   0.00   2.00    43-2  3.00   3.00   0.00   0.00   0.00   0.00    RL-19 0.00   0.00   0.00   0.00   1.00   0.00    10558-432          3.00   3.00   0.00   0.00   0.00   3.00    12396-433          0.00   0.00   0.00   1.00   0.00   0.00    27351 3.00   3.00   0.00   2.00   0.00   0.00    27352 0.00   3.00   0.00   0.00   0.00   0.00    27609-new          3.00   2.00   0.00   0.00   0.00   0.00    33399 1.00   2.00   0.00   1.00   0.00   0.00    Average          1.44   2.00   0.00   0.44   0.11   0.56    Standard          1.51   1.22   0.00   0.73   0.33   1.13    Deviation    __________________________________________________________________________    KEY:    Enamel Treatments    1st Character - Particle Coating    E = Enamel uncoated by polymer    A1 = Enamel coated with polymer A    B1 = Enamel coated with polymer B    C1 = Enamel coated with polymer C    E1 = Enamel coated with polymer E    2nd Character - Saliva Treatment    B = KCL buffer treatment only    S = Saliva treatment    3rd Character - Wash Buffer    KCL = KCL Buffer wash    T20 = KCL + 1% Tween ™ 20 Buffer wash    T8O = KCL + 1% Tween ™ 80 Buffer wash    TP = KCL + 1% Close-up ™ toothpaste extract wash    MW = KCL + 1% Lavoris ™ mouthwash wash

BIOLOGICAL EVALUATION 3 OF COATING SOLUTIONS

Polystyrene assay wells, previously coated with maleic anhydride, weretreated with various solutions as shown below.

i) control, uncoated

ii) coated with a solution of polymer C (7.5% in iso-propanol)

iii) coated with a solution of polymer C (7.5% in iso-propanol) followedby a rinse consisting of a buffer solution containing 1% by weight ofTween 80

iv) coated with a solution of polymer E (7.5% in isopropanol); or

v) coated with a solution of polymer E (7.5% in iso-propanol) followedby a rinse consisting of a buffer solution containing 1% by weight ofTween 80.

An inoculum of S. Challis cells was plated at a concentration of 1×10⁷cells per well. After the standard washing procedures the cells adheringto the wells were counted in a scintillation counter and expressed as apercentage of the original inoculum. These are reported in Table 17 as arelative percent of the control, uncoated substrate (100%).

                  TABLE 17    ______________________________________    Substrate        Retention of Cells    ______________________________________    i)      Control      100    ii)     Polymer C coated                         60    iii)    Polymer C + rinse                          7    iv)     Polymer E coated                         59    v)      Polymer E + rinse                         15    ______________________________________

The above results show that application of a polymer coating decreasesthe adhesion of oral bacteria. Treatment of the coating with asurfactant-containing rinse solution prior to the exposure of thebacteria further reduces the adhesion of the bacteria.

DETAILED DESCRIPTION OF THE DRAWING

To compare the coating of tooth slabs with polymer and PDMS solutions.Dentin slabs were coated either with 7.5% solutions of polymer C inisopropanol (Example 4) or with 7.5% solution of PS 510 polydimethylsiloxane in acetone (comparative Example 1). A solution was prepared bydissolving 0.01 grams of methylene blue in 50 ml of distilled water. Thecoated dentin slabs were immersed in this solution for 5 minutes, thenremoved and rinsed with distilled water. The slabs were air dried andpolaroid photos were taken using an olypus magnifying microscope at7.5×.

The dentin slab as shown in FIG. 1 was clear white on both sidesindicating that no dye was retained on the dentin slab coated withpolymer C. In contrast, FIG. 2 shows that dentin slabs coated with thesiloxane of comparative example 1 experienced retention of the dye onthe surface of the slabs, as indicated by the dark areas.

As noted in the discussion of the Adherence Assay results of BiologicalEvaluation 1, FIGS. 3 and 4 show adherence of bacteria to enamelparticles having either no coating or a coating as set forth below:

1: Uncoated enamel without saliva treatment

2: Uncoated enamel with saliva treatment

3: Enamel coated with B without saliva treatment

4: Enamel coated with B with saliva treatment

5: Enamel coated with A with saliva treatment

6: Enamel coated with C with saliva treatment

7: Enamel coated with E with saliva treatment

8: Negative control

Enamel particles that are provided with coatings show substantialdecrease of adhesion of IgG, OVA and/or P.gin.

EXAMPLE 8

Table 18 below describes the reaction compositions of polymers withdifferent A units. Each of the polymers shown in Table 18 was preparedby a continuous feed polymerization process described below.

                  TABLE 18    ______________________________________                         Advancing Receding    A Unit               Water     Water                        Weight   Contact Contact    Polymer           Monomer      (g)      Angle   Angle    ______________________________________    G      Acrylic Acid 6.00     105.50  68.27    H      Vinyl-phosphonic                        9.00     103.74  61.10           Acid    I      2-Hydroxyethyl                        10.84    103.41  54.58           methacrylate    ______________________________________

To a 250 ml, three-neck, round bottom flask isopropanol (20 ml) wasadded along with a magnetic stir bar. AIBN (0.2 g) was dissolved inisopropanol (60 ml), and this solution was placed in a 60 ml droppingfunnel and attached to the reaction flask. The A unit described in Table18 along with methyl methacrylate (26 g) and PDMS macromer (4 g) weredissolved in isopropanol (28 ml), placed in a second 60 ml droppingfunnel, and attached to the reaction flask. A condenser was placed inthe third neck of the reaction flask. At room temperature the reactionvessel was deoxygenated by bubbling nitrogen gas through the feedsolutions for 15 minutes. The contents of the two funnels were added tothe reaction flask at a steady rate (10 ml/hour) for six hours whilemaintaining the reaction flask at 60° C. under a nitrogen blanket withmild agitation. Following the complete addition of the monomer andinitiator solutions, the reaction flask was maintained at 60° C. andunder nitrogen for an additional three hours.

Following the polymerization of polymers G and H, a quantity of acetonesufficient to dissolve the polymers was independently added to eachreaction mixture. Each polymer was purified by adding each reactionmixture dropwise to a quantity of water four times that of the totalreaction mixture volume with vigorous stirring. Each precipitatedpolymer was removed from the water mixture, and then dried in a vacuumoven for several days at approximately 60° C. The resultant solidpolymers were ground and stored as powders.

Polymer I was used without further purification. The weight percentpolymer in the reaction mixture was determined by gravimetric methods,and then the reaction mixture was diluted to approximately 10% polymerin 50/50 isopropanol/acetone.

The hydrophobicity and hydrophilicity of the polymer coatings describedin Table 18 were characterized by the advancing and receding contactangles of water, respectively. The advancing and receding contact anglesof water were measured using the Wilhelmy plate technique.Polymer-coated glass plates (22 mm×22 mm×0.15 mm) were used as platesfor the measurements. The glass plates were silane treated withgamma-methacryloxypropyltrimethoxysilane ("A-174", OSi Specialties,Inc.) prior to dip coating the plates in the polymer solutions. Theadvancing and receding water contact angles of the coated plates weremeasured using a plate immersion speed of 50 microns/second. The contactangle results in Table 18, which represent the average of two to threereplicate measurements, show that the polymer coatings were morehydrophobic and less hydrophilic than bare, polished enamel (shown inTable 6).

The toothbrush/toothpaste abrasion resistance of the polymers describedin Table 18 on enamel was determined using the following proceduretermed "Method I". Bovine incisors were potted in an epoxide resin. Thebuccal surfaces were then polished with 120 and 600 grit silicon carbidewet/dry sand paper to expose clean, flat enamel surfaces. To furtherclean the polished enamel surfaces, the enamel was acid etched with 10%citric acid in water for 15 seconds, rinsed and dried. The polymers(10%) described in Table 18 were dissolved in the solutions in Table 19and applied to the polished enamel surfaces with a #75 coating rod fromRD Specialties, Inc. The dry polymer films were approximately 5 micronsthick.

Each coated enamel surface was brushed with an ORAL B™ 35 Soft Straighttoothbrush under a load of 2.7 Newtons at a frequency of 3 cycles/seconduntil only 10% of the enamel remained coated with polymer. The enamelsurface and toothbrush were immersed in a slurry of 50/50 by weightCREST™ Regular Flavor toothpaste/distilled water during the brushingprocess.

At regular intervals during brushing the percentage of the polishedenamel surface that remained coated with polymer was determined by astaining procedure. The polished surface was etched with 37% phosphoricacid for one second, rinsed, immersed in a 0.2% aqueous solution of AcidViolet #17 (Aldrich Chemical Company, Inc., Milwaukee, Wis.) forapproximately 30 seconds, rinsed, and dried. The plaque resistantpolymers were relatively unaffected by the phosphoric acid etching stepand were resistant to staining with Acid Violet #17, while the areaswhere no coating remained on the enamel surface showed staining. Thepercentage of the polished surface area that remained coated afterbrushing was determined by visual examination and was reported as thepercentage of the surface that was unstained.

Table 19 below shows the comparison of the toothbrush/toothpasteabrasion resistance of polymers G, H and I. The results, which representthe average of five replicate measurements, show that polymers G, H andI have good resistance to abrasion encountered during tooth brushing.

                  TABLE 19    ______________________________________                       Time to Remove                                    Time to Remove                       50% of the   90% of the                       Polymer Coating                                    Polymer Coating    Polymer          Coating Solvent                       (sec)        (sec)    ______________________________________    G     50/50 iso-propanol/                       250.0        398.0          acetone    H     95/5 acetone/ethanol                       246.0        532.0    I     50/50 isopropanol/                       176.0        306.0          acetone    ______________________________________

EXAMPLE 9

Table 20 below describes the reaction compositions of plaque resistantpolymers with different B units. Each of the polymers in Table 20 wasprepared by charging acrylic acid (6 g), PDMS macromer (4 g), AIBN (0.2g), the described B unit (26 g), and solvent (108 ml) to a 250 ml roundbottom flask. At room temperature the reaction mixture was deoxygenatedby bubbling nitrogen through the mixture for fifteen minutes. Thetemperature of the reaction mixture was then raised to 60° C. with mildagitation. The reaction was carried out under a nitrogen blanket foreight hours.

                  TABLE 20    ______________________________________                             Percentage of                             Enamel Area that    Reaction Composition     Remained Coated    Polymer           B Unit        Solvent     after Brushing    ______________________________________    J      iso-Bornyl    Isopropanol 44.0           Methacrylate    K      Methyl Methacrylate                         Isopropanol 76.5    L      tert-Butyl    Tetrahydrofuran                                     62.5           Methacrylate    ______________________________________

The polymers J and L were purified by independently adding each reactionmixture dropwise to a quantity of water four times that of the totalreaction mixture volume with vigorous stirring. The precipitatedpolymers were removed from the water mixture, and then dried in a vacuumoven for several days at approximately 60° C. The dried polymers wereground to a fine powder and stored. Polymer K was purified by a similarprocedure except that 36 g of acetone was added to the reaction mixtureto dissolve the polymer prior to the dropwise addition of the reactionmixture to water.

The toothbrush/toothpaste abrasion resistance of the polymers describedin Table 20 on enamel was determined using the following proceduretermed "Method II". Bovine incisors were potted in polymethylmethacrylate such that the buccal surfaces were raised above the pottingmaterial. The buccal surfaces were then polished with 120 and 600 gritsilicon carbide wet/dry sand paper to reveal clean, flat enamelsurfaces. To further clean the polished enamel surfaces, the enamel wasacid etched with 10% citric acid in water for 15 seconds, rinsed anddried. Solutions of the polymers (10%) described in Table 20 inisopropanol (polymers J and L) or 50/50 isopropanol/acetone (polymer K)were applied to the polished enamel surfaces with a small brush andallowed to air dry. The coated enamel samples were stored at 37° C., 97%relative humidity ("RH") for 24 hours prior to brushing.

Each coated enamel surface was brushed with an ORAL B™ 35 Soft Straighttoothbrush under a load of 140 g at a frequency of 50 cycles/minute forfifteen minutes. The enamel surface and toothbrush were immersed in aslurry of 50/50 by weight CREST™ Regular Flavor toothpaste/distilledwater during the brushing process.

After brushing, the percentage of the polished enamel surface thatremained coated with polymer was determined using the staining proceduredescribed in Method I in Example 8.

Table 20 shows the comparison of the toothbrush/toothpaste abrasionresistance of polymers with various B units. The results, which were theaverage of two replicates, show that the polymer coatings have goodresistance to abrasion encountered during tooth brushing.

EXAMPLE 10

Table 21 below shows the reaction compositions of plaque resistantpolymers with different relative amounts of A unit, B unit and C unit.Each polymer in Table 21 was prepared by charging the monomers, AIBN(0.2 g), and isopropanol (108 ml) to a 250 ml three-neck, round bottomflask. At room temperature the reaction mixture was deoxygenated bybubbling nitrogen through the mixture for fifteen minutes. The reactionmixture was then raised to 60° C. with mild agitation. The reaction wascarried out under a nitrogen blanket for eight hours.

                                      TABLE 21    __________________________________________________________________________    Reaction Composition            Time to               B Unit                     C Unit                          Advancing                               Receding                                    Remove         A Unit               Methyl                     PDMS Water                               Water                                    the         Acrylic Acid               Methacrylate                     Macromer                          Contact                               Contact                                    Coating    Polymer         (g)   (g)   (g)  Angle                               Angle                                    (sec)    __________________________________________________________________________    M    2.60  25.20 7.20 105.17                               70.50                                    174    N    1.98  33.22 0.80 96.67                               63.75                                    477    K    6.00  26.00 4.00 100.67                               71.00                                    412    O    1.98  30.02 4.00 101.33                               75.25                                    200    P    6.00  29.20 0.80 98.67                               67.33                                    173    __________________________________________________________________________

Following the polymerization of the monomers described in Table 21, aquantity of acetone sufficient to dissolve the polymers was added toeach reaction mixture. Each polymer was then purified by adding eachreaction mixture dropwise to a quantity of water four times that of thetotal reaction mixture volume with vigorous stirring. The precipitatedpolymer was removed from the water mixture, and then dried in a vacuumoven for several days at approximately 60° C. The resultant solidpolymers were ground and stored as powders.

The hydrophobicity and hydrophilicity of the polymer coatings describedin Table 21 were characterized by the advancing and receding contactangles of water, respectively. The advancing and receding contact anglesof water were measured using the sessile drop technique. The testspecimens for sessile drop contact angle determinations were prepared byfirst potting bovine incisors in an epoxide resin. The buccal surfaceswere then polished with 120 and 600 grit silicon carbide wet/dry sandpaper, 6 and 3 micron diamond pastes, and a 0.05 micron alumina slurryto expose clean, flat enamel surfaces. Solutions of the plaque resistantpolymers (10%) in Table 21 in 50/50 isopropanol/acetone were applied tothe polished enamel surfaces with a small brush. The contact angleresults in Table 21, which represent the average of two replicatemeasurements, show that the polymer coatings were more hydrophobic andless hydrophilic than bare, polished enamel (shown in Table 6).

The toothbrush/toothpaste abrasion resistance of the polymers in Table21 was measured using Method I except that a #40 coating rod from RDSpecialties, Inc. was used to apply the polymer solutions to theprepared enamel surfaces, yielding a dry film thickness of approximately3 microns. The polymer films were cast from 10% polymer solutions in50/50 isopropanol/acetone. The teeth were brushed until the polymerswere completely removed. The toothbrush/toothpaste abrasion resistanceresults in Table 21, which represent the average of three to fivereplicate measurements, show that the polymer coatings have goodresistance to abrasion encountered during tooth brushing.

EXAMPLE 11

The adherence of cariogenic bacteria to polymers N and K of Example 10were determined using the following procedure. Clean bovine teeth wereacid etched with 10% citric acid for 15 seconds, rinsed and dried. Thecrowns of the acid etched teeth were then dip coated into 10% polymersolutions in 50/50 isopropanol/acetone and allowed to air dry.

The polymer coated bovine teeth were placed in 10 mm×30 mm polypropylenetest tubes and held in place using 3M™ Imprint™ Impressioning Material(from 3M). The teeth were placed such that only the crown area of thetooth was exposed. The teeth were then placed crown end down into thewells of a 24-well tissue culture plate (Costar, Inc., Cambridge, Mass.)and whole human saliva (2.3 ml) was added to each well to cover thecrown. The teeth were incubated one hour with shaking at roomtemperature. "Mutans streptococci" (American Type Culture Collection,Rockville, Md.) washed in KCl buffer (0.1M NaCl, 0.05M KCl, 1 mM KH₂PO₄, 0.1 mM MgCl₂, 1 mM CaCl₂, pH 7.0) were added to the saliva (10⁹ pertooth) and incubated an additional two hours at room temperature withshaking. The teeth were then washed twice with either KCl buffer or KClbuffer supplemented with 0.3% TWEEN-80 (Sigma, Inc., St. Louis, Mo.).The teeth were removed from the impressioning material and placed crownend down into new 24-well plates. KCl buffer or KCl buffer with TWEEN-80(2 ml) was added to each well and the teeth washed twice more. DNAextraction buffer (0.4M NaOH, 10 mM ethylenediaminetetraacetic acid(EDTA)) (2.3 ml) was added to each well and the plates heated to95°-100° C. for 12 minutes. The solubilized DNA was removed from thewells and divided into three equal portions. Each portion was added tothe well of a slot-blot apparatus where the levels of bacterial DNA ineach sample were determined. The teeth were then removed from the platesand numbered.

The level of bacterial DNA in each sample was determined using thefollowing DNA slot-blot procedure. A sheet of Zeta-Probe hybridizationmembrane (BioRad Laboratories, Inc., Richmond, Calif.) was prepared byimmersing the membrane in distilled water. The wet membrane was thenmounted in a slot-blot apparatus (Minifold II, Schleicher & Schuell,Inc.), vacuum applied and each well rinsed with 0.5 ml of TE buffer (10mM tris(hydroxymethyl)aminomethane hydrochloride (TRIZMA™ hydrochloride,Sigma, Inc.), 1 mM EDTA, pH 8.0). Solubilized DNA samples were added toeach well and washed once with 0.4M NaOH. The vacuum source wasdisconnected after all liquid had been pulled through the membrane, theapparatus was disassembled and the DNA were immobilized on the semi-drymembrane by exposure to UV light for 3 minutes (StratLinker, Stratagene,Inc., LaJolla, Calif.). The membranes were rinsed briefly in 0.3M NaCl,0.03M sodium citrate and dried in a 37° C. incubator. The dry membraneswere placed in a glass hybridization chamber and 15 ml ofpre-hybridization solution (Life Technologies, Inc, Grand Island, N.Y.)added. The tubes were rotated at 65° C. for one hour in thehybridization oven (Hybridizer 700, Stratagene, Inc.).Digoxegenin-labeled whole genomic probes for the organism being tested(150 ng) were added to pre-hybridization solution (15 ml). The dilutedprobes were boiled for 12 minutes. The pre-hybridization solution wasthen removed from the glass hybridization chambers and replaced by thediluted probe solution. The slot-blot was incubated overnight at 65° C.with the probe.

The slot-blot membranes incubated overnight with digoxigenin-labeledprobes were removed from the hybridization oven and washed twice for 5minutes in 0.3M NaCl, 0.03M sodium citrate with 0.1% sodium dodecylsulphate ("SDS") in a glass tray mounted on a shaker platform at roomtemperature. The membranes were washed twice in 50 ml of 15 mM NaCl, 1.5mM sodium citrate with 0.1% SDS in the hybridization oven at 65° C. for30 minutes. The membranes were then placed in a glass tray and washedfor 2 minutes at room temperature in maleic acid buffer (0.15M NaCl,0.1M maleic acid, pH 7.5). The membranes were incubated for 1 hour atroom temperature in maleic acid buffer, with 10% skim milk proteins (KPLLaboratories, Gaithersburg, Md.) added, to block nonspecific reactantsites on the membrane. Anti-Digoxigenin antibody labeled with alkalinephosphatase (Boehringer Mannheim, Inc., Indianapolis, Ind.) was diluted1:5000 in maleic acid buffer with 10% skim milk proteins and added tothe membranes for 1 hour at room temperature. The antibody solution wasremoved and the membrane washed twice for 15 minutes in maleic acidbuffer with 0.3% TWEEN-20. After removal of the wash buffer the membranewas equilibrated for 5 minutes in enzyme substrate buffer (0.1M TRIZMAhydrochloride, pH 9.5). Bromochloroindole phosphate/nitrobluetetrazolium enzyme substrate solution (KPL Laboratories, Inc.) was addedand the membrane incubated in the dark at room temperature for 30minutes. Color development was stopped by transfer of the membrane to TEbuffer for 5 minutes followed by soaking in distilled water for 5-10minutes. The membranes were then placed on paper towels to dry.

Dried membranes were placed on the transport tray of a densitometer(Model 325, Molecular Dynamics, Inc., Sunnyvale, Calif.) and scanned.The data was collected as a digital file using the Molecular DynamicsImageQuant™ software. The net optical density of each slot wasdetermined and compared to a standard curve of microbial DNA run on eachmembrane. The microbial equivalents of each slot was calculated andnormalized by the tooth crown surface area determined by profilometrytechniques.

The bacterial adherence results for polymers N and K are shown in Table22 for four strains of "Mutans streptococci" from the American TypeCulture Collection (ATCC), Rockville, Md. Table 22 lists the percentreduction in bound bacteria compared to uncoated enamel. Four species ofbacteria were evaluated with and without TWEEN-80 included in the KClwashes. When Tween-80 was included in the KCl washes of the polymercoated teeth, Tween-80 was also included in the KCl washes of the bareenamel control teeth. The results, which represent the average of fivemeasurements, show that when the plaque resistant coatings were appliedto enamel, a significant reduction in the binding of cariogenic bacteriawas achieved.

                                      TABLE 22    __________________________________________________________________________    Percent Reduction in Adherence of                        Percent Reduction in Adherence of    Bacteria Compared to Uncoated                        Bacteria Compared to Uncoated    Enamel              Enamel/With TWEEN-80 Wash        ATCC            ATCC                ATCC                    ATCC                        ATCC                            ATCC                                ATCC                                    ATCC    Polymer        10558            12392                33999                    27352                        10558                            12392                                33999                                    27352    __________________________________________________________________________    N   96.84            87.41                65.45                    99.80                        93.69                            97.49                                69.09                                    87.41    K   98.42            92.06                23.77                    93.69                        84.15                            96.84                                47.37                                    90.00    __________________________________________________________________________

EXAMPLE 12

Table 23 below describes the reaction compositions of plaque resistantpolymers with various D units, including A-174 and the alkoxy-silanesshown below. ##STR16##

Table 23 also compares a polymer prepared without a D unit. Each of thesix polymers in Table 23 was prepared by charging acrylic acid (6 g),iso-butyl methacrylate, PDMS macromer (4 g), the described D unit, AIBN(0.2 g), and isopropanol (108 ml) to a 250 ml round bottom flask. Atroom temperature the reaction mixture was deoxygenated by bubblingnitrogen through the mixture for fifteen minutes. The reaction mixturewas then raised to 60° C. with mild agitation and carried out under anitrogen blanket for eight hours.

Polymer B was purified by adding the reaction mixture dropwise to aquantity of water four times that of the total reaction mixture volumewith vigorous stirring. The precipitated polymer was removed from thewater mixture, and then dried in a vacuum oven for several days atapproximately 60° C.

The D unit-containing polymers in Table 23 (polymers Q-U) were usedwithout further purification. The weight percent polymer in eachreaction mixture was determined by gravimetric methods, and then eachreaction mixture was diluted to 10% polymer in isopropanol.

The hydrophobicity and hydrophilicity of the polymer coatings describedin Table 23 were characterized by the advancing and receding contactangles of water, respectively. The advancing and receding contact anglesof water were measured using the Wilhelmy plate technique, and theresults are shown in Table 23. The results, which represent the averageof two measurements, show that the polymer coatings were morehydrophobic and less hydrophilic than bare, polished enamel (shown inTable 6).

The toothbrush/toothpaste abrasion resistance of the polymers describedin Table 23 on enamel was determined using Method II. Solutions of thepolymers (10%) in Table 23 in isopropanol were applied to the polishedenamel surfaces with a small brush and allowed to air dry. The sampleswere stored in a humidity oven at 37° C. for at least 24 hours prior tobrushing. The results, which represent the average of at least twomeasurements, show an increase in the toothbrush/toothpaste abrasionresistance of the polymer coatings with the addition of the D unit.

                                      TABLE 23    __________________________________________________________________________    B Unit               Advancing                               Receding                                    Percentage of    iso-Butyl   D Unit   Water Water                                    Enamel Area that         Methacrylate                     Weight                         Contact                               Contact                                    Remained Coated    Polymer         (g)    Monomer                     (g) Angle Angle                                    After Brushing    __________________________________________________________________________    B    26.0   None 0.00                         107.82                               68.45                                    0.0    Q    24.7   A-174                     1.30                         104.69                               75.08                                    15.6    R    23.4   A-174                     2.60                         107.39                               75.30                                    25.0    S    24.7   (i)  2.60                         104.50                               76.38                                    12.5    T    24.7   (ii) 1.75                         103.52                               73.70                                    8.0    U    24.7   (iii)                     1.97                         103.38                               81.33                                    31.0    __________________________________________________________________________

EXAMPLE 13

Table 24 below shows the advancing and receding water contact angles ofpolymers Q-U of Example 12 when a condensation catalyst was added to thecoating solution. The Wilhelmy plate technique was used to determine thecontact angles. Stannous octoate was used as the condensation catalyst(5% of the polymer weight). The results in Table 24, which represent theaverage of two measurements, show that the polymer coatings were morehydrophobic and less hydrophilic than bare, polished enamel (shown inTable 6).

Also shown in Table 24 is the toothbrush/toothpaste abrasion resistanceof polymers Q-U on enamel determined using Method II when a condensationcatalyst was added to the coating solution (5% by weight of thepolymer). Solutions of the plaque resistant polymers (10%) inisopropanol were prepared using condensation catalyst stannous octoate,dibutyl tin dilaurate, or triethylene diamine. The coating solutionswere applied to polished enamel surfaces with a small brush and allowedto air dry. The samples were stored in a humidity oven at 37° C. for atleast 24 hours prior to brushing. The results, which represent theaverage of at least two measurements, show that the inclusion of acrosslinkable alkoxy-silane D unit significantly increased abrasionresistance of the coating.

                                      TABLE 24    __________________________________________________________________________                      Percentage of Enamel Area that Remained Coated    Advancing  Receding                      After Brushing        Water Contact               Water Contact                      Stannous                            Dibutyl Tin                                    Triethylene    Polymer        Angle  Angle  Octoate                            Dilaurate                                    Diamine    __________________________________________________________________________    Q   103.19 80.11  84.4  12.5    85.0    R   107.30 79.76  90.0  70.0    50.0    S   103.02 79.79  40.3  --      --    T   102.55 77.91  66.3  --      --    U   102.00 79.19  60.0  --      --    __________________________________________________________________________

EXAMPLE 14

Table 25 below shows the advancing and receding water contact angles ofpolymers Q and R of Example 12 when a bridging compound for thecrosslinking of the D units was added to the coating solution. Thebridging compound, termed "PHS", shown in Table 25 was obtained fromA-174 after hydrolysis and partial condensation. The concentrations ofPHS shown in Table 25 are weight percentages based on the polymer weightin solution. The Wilhelmy plate technique was used to determine thecontact angles. The results in Table 25, which represent the average oftwo measurements, show that the polymer coatings were more hydrophobicand less hydrophilic than bare, polished enamel (shown in Table 6).

                                      TABLE 25    __________________________________________________________________________                                  Percentage of the Enamel    Advancing Water Contact       Area that Remained Coated    Angle           Receding Water Contact Angle                                  after Brushing        10% 20% 30% 10% 20%  30%  10% 20% 30%    Polymer        PHS PHS PHS PHS PHS  PHS  PHS PHS PHS    __________________________________________________________________________    Q   107.34            107.47                107.19                    72.53                        70.49                             69.78                                  50.0                                      69.0                                          87.5    R   107.43            107.30                106.78                    71.87                        74.58                             72.23                                  100.0                                      100.0                                          97.0    __________________________________________________________________________

Tables 26 and 27 below show the advancing and receding water contactangles, respectively, of polymers Q and R of Example 12 when Y-11597(tris N-(trimethoxysilyl)propyl!isocyanurate, commercially availablefrom OSi Specialties, Inc.) was added to the coating solution. Theamount in moles of this bridging compound added to the coating solutionwas calculated on the basis of one mole of A-174 unit in the polymer.Tables 26 and 27 also show the effect of a condensation catalyst inconjunction with a bridging compound on the contact angles. Thecondensation catalyst used was stannous octoate at a concentration of 5%based on the polymer weight in solution. The Wilhelmy plate techniquewas used to determine the contact angles. The results in Tables 26 and27, which represent the average of two measurements, show that thepolymer coatings were more hydrophobic and less hydrophilic than bare,polished enamel (shown in Table 6).

                                      TABLE 26    __________________________________________________________________________    Advancing Water Contacte Angle    No Stannous Octoate   With Stannous Octoate         0.5 mole               1.0 mole                     2.0 moles                          0.5 mole                                1.0 mole                                     2.0 moles    Polymer         Y-11597               Y-11597                     Y-11597                          Y-11597                                Y-11597                                     Y-11597    __________________________________________________________________________    Q    107.66               107.13                     107.26                          107.69                                107.71                                     107.41    R    107.53               107.64                     107.85                          107.66                                107.53                                     107.13    __________________________________________________________________________

                                      TABLE 27    __________________________________________________________________________    Advancing Water Contact Angle    No Stannous Octoate   With Stannous Octoate         0.5 mole               1.0 mole                     2.0 moles                          0.5 mole                                1.0 mole                                     2.0 moles    Polymer         Y-11597               Y-11597                     Y-11597                          Y-11597                                Y-11597                                     Y-11597    __________________________________________________________________________    Q    74.87 75.73 73.31                          75.76 72.97                                     74.26    R    74.67 74.02 74.18                          73.25 70.53                                     68.49    __________________________________________________________________________

The toothbrush/toothpaste abrasion resistance of polymers Q and R onenamel determined using Method II when the bridging compound PHS orY-11597 was added to the coating solution is shown in Tables 25 and 28,respectively. Table 28 also shows the effect of a condensation catalystin conjunction with a bridging compound. Solutions of the polymers (10%)in isopropanol were prepared with different amounts of the bridgingcompound and, optionally, with a condensation catalyst. The condensationcatalyst used was stannous octoate at a concentration of 5% based on thepolymer weight in solution. The coating solutions were applied topolished enamel surfaces with a small brush and allowed to air dry. Thesamples were stored in a humidity oven at 37° C. for at least 24 hoursprior to brushing. The results, which represent the average of at leasttwo measurements, show that the inclusion of a crosslinkablealkoxy-silane D unit significantly increased abrasion resistance of thecoating.

                                      TABLE 28    __________________________________________________________________________    Percentage of the Enamel Area that Remained Coated after Brushing    No Stannous Octoate   With Stannous Octoate         0.5 mole               1.0 mole                     2.0 moles                          0.5 mole                                1.0 mole                                     2.0 moles    Polymer         Y-11597               Y-11597                     Y-11597                          Y-11597                                Y-11597                                     Y-11597    __________________________________________________________________________    Q    87.5  100.0 82.5 25.0  100.0                                     100.0    R    66.3  100.0 100.0                          100.0 100.0                                     72.5    __________________________________________________________________________

EXAMPLE 15

The adherence of cariogenic bacteria to the polymers Q and S-U fromExample 12 with and without the condensation catalyst stannous octoate(5% based on the polymer weight in solution) were measured using theprocedure described in Example 11. The results are shown in Table 29below for a strain of Streptococcus sobrinus (ATCC 27351) and a strainof Streptococcus gordonii (ATCC 10558). Table 29 lists the percentreduction in bound bacteria compared to uncoated enamel. Two species ofbacteria were evaluated with and without TWEEN-80 included in the KClwashes. When Tween-80 was included in the KCl washes of the polymercoated teeth, Tween-80 was also included in the KCl washes of the bareenamel control teeth. The results, which represent the average of fivereplicate measurements, show that when the plaque resistant coatingswere applied to enamel a significant reduction in the binding ofcariogenic bacteria was achieved.

                                      TABLE 29    __________________________________________________________________________                                     % Reduction                              % Reduction in                                     in Adherence    % Reduction in % Reduction in                              Adherence of                                     of ATCC    Adherence of ATCC                   Adherence of ATCC                              ATCC 27351                                     10558 with    27351          10558      with TWEEN-                                     TWEEN-80        No    With No    With 80     With        Stannous              Stannous                   Stannous                         Stannous                              With Stannous                                     Stannous    Polymer        Octoate              Octoate                   Octoate                         Octoate                              Octoate                                     Octoate    __________________________________________________________________________    Q   99.23 99.99                   77.92 70.04                              99.30  99.46    S   99.51 98.50                   85.70 92.17                              --     --    T   95.10 97.77                   5.19  68.79                              --     --    U   94.79 87.69                   87.07 86.05                              --     --    __________________________________________________________________________

EXAMPLE 16

Table 30 below shows the reaction composition of a polymer with B unitmethyl methacrylate and D unit A-174. For comparison, Table 30 containsthe reaction composition of a similar polymer prepared without thecorresponding D unit. Both polymers shown in Table 30 were prepared bythe continuous feed polymerization process described in Example 8. Themonomer feeds consisted of acrylic acid (6 g), methyl methacrylate (26g), PDMS macromer (4 g), and optionally the A-174 D unit (2.6 g) inisopropanol (28 ml). The initiator feed consisted of AIBN (0.2 g) inisopropanol (60 ml). The monomer and initiator feeds were placed inrespective 60 ml dropping funnels and the funnels were attached to a 250ml, three-neck, round bottom flask. A small quantity of isopropanol (20ml) and a magnetic stir bar were charged to the 250 ml round bottomflask initially. A condenser was placed in the third neck of thereaction flask. At room temperature the reaction vessel was deoxygenatedby bubbling nitrogen gas through the feed solutions for 15 minutes. Thecontents of the two funnels were added to the reaction flask at a steadyrate (10 ml/hour) for six hours while maintaining the reaction flask at60° C. under a nitrogen blanket with mild agitation. Following thecomplete addition of the monomer and initiator solutions, the reactionflask was maintained at 60° C. and under nitrogen for an additionalthree hours.

                                      TABLE 30    __________________________________________________________________________                                       Time to                                       Remove                                       90% of                      Condensation                             Advancing                                  Receding                                       the    D Unit      Bridging                      Catalyst                             Water                                  Water                                       Polymer            Weight                Compound                      Stannous                             Contact                                  Contact                                       Coating    Polymer        Unit            (g) PHS   Octoate                             Angle                                  Angle                                       (sec)    __________________________________________________________________________    K   None            0.00                None  None   104.47                                  69.02                                       342.5    V 1 A-174            2.60                None  None   104.73                                  70.81                                       378.0      2 A-174            2.60                10% or                      None   103.32                                  70.84                                       276.0                polymer                weight      3 A-174            2.60                None  5% of polymer                             103.42                                  71.07                                       1340.0                      weight    __________________________________________________________________________

Following the polymerization of polymer K, acetone (50 ml) was added tothe reaction mixture to dissolve the polymer. The polymer was thenpurified by the dropwise addition of the reaction mixture to a quantityof water four times that of the total reaction mixture volume withvigorous stirring. The precipitated polymer was removed from the watermixture, and then dried in a vacuum oven for several days atapproximately 60° C. The resultant solid polymer was ground and storedas a powder.

Polymer V was used without further purification. The percent polymeryield was determined by gravimetric methods to be 76.4%. The reactionmixture was then diluted to 10% polymer in 50/50 isopropanol/acetone.

Table 30 also shows the advancing and receding water contact angles ofpolymer K and polymer V with and without the bridging compound PHS andthe condensation catalyst stannous octoate. The contact angles weremeasured using the Wilhelmy plate technique. The results, whichrepresent the average of two measurements, show that the polymercoatings were more hydrophobic and less hydrophilic than bare, polishedenamel (shown in Table 6).

The toothbrush/toothpaste abrasion resistance of polymer K, and polymerV with and without the bridging compound PHS and the condensationcatalyst stannous octoate on enamel was determined using Method I.Solutions of the polymers (10%) described in Table 30 in 50/50isopropanol/acetone were applied to the polished enamel surfaces with a#75 coating rod. The dry polymer films were approximately 5 micronsthick. The coated teeth were stored in a humidity oven at 37° C. for 70hours at 95% RH prior to tooth brushing. The coated teeth were brusheduntil only 10% of the enamel remained coated with polymer. The resultsin Table 30, which represent the average for five replicatemeasurements, show that the inclusion of a crosslinkable alkoxy-silane Dunit significantly increased the abrasion resistance of the coating.

What is claimed:
 1. An orthodontic device having a coating comprising apolymer comprising repeating unitsA) 1-80% by weight of a polar orpolarizable group B) 0-98% by weight of a modulating group C) 1-40% byweight of a hydrophobic graft polysiloxane chain having molecular weightof at least 500 applied thereto, which polysiloxane chain has is derivedfrom a monomer having the general formula

    X(Y).sub.n- Si(R).sub.3-m Z.sub.m

wherein X is a vinyl group copolymerizable with the A and B monomers; Yis a divalent linking group n is zero or 1; m is an integer of from 1 to3; R is hydrogen, lower alkyl, aryl, or alkoxy; Z has the generalformula ##STR17## where R⁹ and R¹¹ are independently lower alkyl, aryl,or fluoroalkylR¹⁰ may be alkyl, alkoxy, alkylamino, aryl, hydroxyl, orfluoroalkyl; and e is an integer form about 5 to about
 700. 2. Anorthodontic device having a coating comprising a polymer comprisingrepeating unitsA) 1-80% by weight of a polar or polarizable group B)0-98% by weight of a modulating group C) 1-40% by weight of ahydrophobic graft polysiloxane chain having molecular weight of at least500, which polysiloxane chain has is derived from a monomer having thegeneral formula

    X(Y).sub.n- Si(R).sub.3-m Z.sub.m

wherein X is A vinyl group copolymerizable with the A and B monomers; Yis a divalent linking group n is zero or 1; m is an integer of from 1 to3; R is hydrogen, lower alkyl, aryl, or alkoxy; Z has the generalformula ##STR18## where R⁹ and are R¹¹ independently lower alkyl, aryl,or fluoroalkylR¹⁰ may be alkyl, alkoxy, alkylamino, aryl, hydroxyl, orfluoroalkyl, and e is an integer from about 5 to about 700, wherein saidpolymer contains at least one silane moiety that is capable ofundergoing a condensation reaction.
 3. The orthodontic device of claim2, wherein the silane moiety is present in 0.1-30 mole percent of thepolymer.
 4. The orthodontic device of claim 2, wherein the silane moietyhas the formula

    --Si(R.sup.12).sub.i T.sub.j

where R¹² is H or lower alkyl; i is an integer from 0-2; j is an integerfrom 1-3; i+j=3; and T is hydroxy or a hydrolyzable group selected fromthe group consisting of halogen atoms, alkoxy, alkenoxy, acyloxy,carboxy, amino, amido, dialkyliminooxy, ketoxime, and aldoxime.
 5. Theorthodontic device of claim 2, said polymer comprising repeating unitsA)1-80% by weight of a polar or polarizable group, B) 0-98% by weight of amodulating group, C) 1-40% by weight of a hydrophobic graft polysiloxanechain having molecular weight of at least 500, which polysiloxane chainhas is derived from a monomer having the general formula

    X(Y).sub.n- Si(R).sub.3-m Z.sub.m

wherein X is a vinyl group copolymerizable with the A and B monomers; Yis a divalent linking group n is zero or 1; m is an integer of from 1 to3; R is hydrogen lower alkyl, aryl, or alkoxy; Z has the general formula##STR19## where R⁹ and R¹¹ are independently lower alkyl, aryl, orfluoroalkylR¹⁰ may be alkyl, alkoxy, alkylamino, aryl, hydroxyl, orfluoroalkyl, and e is an integer from about 5 to about 700, D) 1-50% byweight of a group having the formula

    X(Y)n--Si(R12)iTj

where X is a vinyl group copolymerizable with the A and B monomers; Y isa polyvalent linking group; n is zero or 1; R12 is H or lower alkyl; iis an integer from 0-2; j is an integer from 1-3; i+j=3; and T is ahydroxy or a hydrolyzable group selected from the group consisting ofhalogen atoms, alkoxy, alkenoxy, acyloxy, carboxy, amino, amido,dialkyliminooxy, ketoxime and aldoxime.
 6. The orthodontic device ofclaim 5, wherein T is selected from the group consisting of alkoxy,alkenoxy, acyloxy, ketoxime and aldoxime.
 7. The orthodontic device ofclaim 5, wherein T is an alkoxy group.
 8. The orthodontic device ofclaim 2, said orthodontic device additionally comprising a catalyst thatpromotes the condensation of reactive silane moieties.
 9. Theorthodontic device of claim 8, wherein said catalyst is selected fromthe group consisting of organometallic catalysts containing metals ofgroup III-A, IV-A, V-A, VI-A, VIII-A, I-B, II-B, III-B, IV-B and V-B.10. The orthodontic device of claim 9, wherein said catalyst is selectedfrom the group consisting of tin dioctoate, tin naphthenate, dibutyltindilaurate, dibutyltin diacetate, dibutyltin dioxide, dibutyl tindioctoate, zirconium chelates, aluminum chelates, aluminum titanates,titanium isopropoxide and mixtures thereof.
 11. The orthodontic deviceof claim 8, wherein said catalyst is selected from the group consistingof triethylene diamine, p-toluene sulfonic acid, n-butyl phosphoricacid, and mixtures thereof.
 12. The orthodontic device of claim 2, saidorthodontic device additionally comprising a compound comprising atleast two condensation silicone reaction sites that are capable ofundergoing a condensation reaction.
 13. The orthodontic device of claim12, wherein said compound has the formula

    Y-- Si (R.sup.12).sub.i T.sub.j !.sub.k

where Y is a polyvalent linking group; R¹² is H or lower alkyl; i is aninteger from 0-2; j is an integer from 1-3; i+j=3; k=2-50; and T is ahydroxy or a hydrolyzable group selected from the group consisting ofhalogen atoms, alkoxy, alkenoxy, acyloxy, carboxy, amino, amido,dialkyliminooxy, ketoxime and aldoxime.
 14. The orthodontic device ofclaim 13, wherein T is selected from the group consisting of alkoxy,alkenoxy, acyloxy, ketoxime and aldoxime.
 15. The orthodontic device ofclaim 13, wherein T is an alkoxy group.
 16. The orthodontic device ofclaim 12, wherein said compound is the product of hydrolysis and partialcondensation of gamma-methacryloxypropyl trimethyloxy silane.
 17. Theorthodontic device of claim 12, wherein said compound has the formula##STR20## wherein R¹⁴ is --(CH₂)₃ --Si(OCH₃)₃.
 18. The orthodonticdevice of claim 12, said orthodontic device additionally comprising acatalyst that promotes the condensation of reactive silane moieties. 19.The orthodontic device of claim 13, wherein said catalyst is selectedfrom the group consisting of organometallic catalysts containing metalsof group III-A, IV-A, V-A, VI-A, VIII-A, I-B, II-B, III-B, IV-B and V-B.20. The orthodontic device of claim 19, wherein said catalyst isselected from the group consisting of tin dioctoate, tin naphthenate,dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioxide, dibutyltin dioctoate, zirconium chelates, aluminum chelates, aluminumtitanates, titanium isopropoxide and mixtures thereof.
 21. Theorthodontic device of claim 18, wherein said catalyst is selected fromthe group consisting of triethylene diamine, p-toluene sulfonic acid,n-butyl phosphoric acid, and mixtures thereof.